2015 day 21.

.gitignore

@@ -1 +1,2 @@
 venv
+__pycache__

2022/day1.py

@@ -1,20 +0,0 @@
-# -*- encoding: utf-8 -*-
-
-import sys
-
-lines = sys.stdin.readlines()
-
-# we store the list of calories for each elf in values, and we use the last element
-# of values to accumulate
-values: list[int] = [0]
-for line in lines:
-    if not line.strip():
-        values = values + [0]
-    else:
-        values[-1] += int(line.strip())
-
-# part 1
-print(f"answer 1 is {max(values)}")
-
-# part 2
-print(f"answer 2 is {sum(sorted(values)[-3:])}")

2022/day20.py

@@ -1,70 +0,0 @@
-# -*- encoding: utf-8 -*-
-
-import sys
-
-
-class Number:
-    index: int
-    value: int
-
-    def __init__(self, index: int, value: int):
-        self.index = index
-        self.value = value
-
-    def __eq__(self, other):
-        if isinstance(other, Number):
-            return self.index == other.index
-        elif isinstance(other, int):
-            return self.value == other
-        return False
-
-    def __hash__(self):
-        return hash(self.index)
-
-    def __str__(self):
-        return str(self.value)
-
-    def __repr__(self):
-        return str(self)
-
-
-def decrypt(numbers: list[Number], key: int, rounds: int) -> int:
-
-    numbers = numbers.copy()
-    original = numbers.copy()
-    numbers2index = {number: number.index for number in numbers}
-
-    def swap(lhs: Number, rhs: Number):
-        i1, i2 = numbers2index[lhs], numbers2index[rhs]
-        numbers[i1], numbers[i2] = numbers[i2], numbers[i1]
-        numbers2index[lhs], numbers2index[rhs] = i2, i1
-
-    def move(index: int, value: int):
-        assert value >= 0
-        while value > 0:
-            if index == len(numbers) - 1:
-                swap(numbers[0], numbers[-1])
-                index, value = 0, value - 1
-            else:
-                swap(numbers[index + 1], numbers[index])
-                index, value = index + 1, value - 1
-
-    for _ in range(rounds):
-        for number in original:
-            index = numbers2index[number]
-            move(index, (number.value * key) % (len(numbers) - 1))
-
-    index_of_0 = numbers.index(0)
-    return sum(
-        numbers[(index_of_0 + offset) % len(numbers)].value * key
-        for offset in (1000, 2000, 3000)
-    )
-
-
-numbers = [Number(i, int(x)) for i, x in enumerate(sys.stdin.readlines())]
-
-answer_1 = decrypt(numbers, 1, 1)
-print(f"answer 1 is {answer_1}")
-
-answer_2 = decrypt(numbers, 811589153, 10)
-print(f"answer 2 is {answer_2}")

README.md

@@ -1,7 +1,36 @@
-# Advent Of Code
+# Holt59 - Advent Of Code
 
-To run any script, you need to pipe the input:
+Installation (with [`poetry`](https://python-poetry.org/)):
 
 ```bash
-cat 2022/inputs/day2.txt | python 2022/day2.py
+poetry install
+```
+
+To run any day:
+
+```bash
+holt59-aoc $day
+```
+
+You can use `-v` / `--verbose` for extra outputs in some case, `-t` / `--test` to run
+the code on the test data (one of the test data if multiple are present) or even
+`-u XXX` / `--user XXX` to run the code on a specific input after putting the input
+file under `src/holt59/aoc/inputs/XXX/$year/$day`.
+
+Full usage:
+
+```bash
+usage: Holt59 Advent-Of-Code Runner [-h] [-v] [-t] [-u USER] [-i INPUT] [-y YEAR] day
+
+positional arguments:
+  day                   day to run
+
+options:
+  -h, --help            show this help message and exit
+  -v, --verbose         verbose mode
+  -t, --test            test mode
+  -u USER, --user USER  user input to use
+  -i INPUT, --input INPUT
+                        input to use (override user and test)
+  -y YEAR, --year YEAR  year to run
 ```

pyproject.toml

@@ -0,0 +1,52 @@
+[tool.poetry]
+name = "holt59-advent-of-code"
+version = "0.1.0"
+description = ""
+authors = ["Mikael CAPELLE <capelle.mikael@gmail.com>"]
+license = "MIT"
+readme = "README.md"
+packages = [{ include = "holt59", from = "src" }]
+
+[tool.poetry.dependencies]
+python = "^3.10"
+numpy = "^1.26.2"
+tqdm = "^4.66.1"
+parse = "^1.20.0"
+scipy = "^1.11.4"
+ortools = "^9.8.3296"
+sympy = "^1.12"
+networkx = "^3.2.1"
+
+[tool.poetry.scripts]
+holt59-aoc = "holt59.aoc.__main__:main"
+
+[tool.poe.tasks]
+lint-black = "black --check --diff src tests typings"
+lint-isort = "isort -c src tests typings"
+lint-ruff = "ruff src tests typings"
+lint-flake8 = "flake8 src tests typings"
+lint-pyright = "pyright src tests"
+lint-all.sequence = [
+    "lint-black",
+    "lint-isort",
+    "lint-flake8",
+    "lint-ruff",
+    "lint-pyright",
+]
+lint-all.ignore_fail = "return_non_zero"
+
+[tool.poetry.group.dev.dependencies]
+flake8 = "^6.1.0"
+flake8-black = "^0.3.6"
+black = "^23.12.0"
+pyright = "^1.1.341"
+mypy = "^1.7.1"
+isort = "^5.13.2"
+ruff = "^0.1.8"
+poethepoet = "^0.24.4"
+ipykernel = "^6.27.1"
+networkx-stubs = "^0.0.1"
+
+[build-system]
+requires = ["poetry-core"]
+build-backend = "poetry.core.masonry.api"

run.ps1

@@ -1,5 +1,12 @@
-param([switch]$Test, $day)
+param(
+    [switch]$Test,
+    [PSDefaultValue()]
+    [Parameter(Mandatory = $false)]
+    $Year = 2023,
+    [Parameter(Mandatory = $true, Position = 0)]
+    $Day)
 
 $folder = $Test ? "tests" : "inputs"
 
-Get-Content ".\2022\$folder\day$day.txt" | python ".\2022\day$day.py"
+$env:AOC_VERBOSE = $VerbosePreference -eq "Continue"
+Get-Content ".\$Year\$folder\day$Day.txt" | python ".\$Year\day$Day.py"

src/holt59/aoc/2015/day1.py

@@ -0,0 +1,10 @@
+import sys
+
+line = sys.stdin.read().strip()
+
+floor = 0
+floors = [(floor := floor + (1 if c == "(" else -1)) for c in line]
+
+
+print(f"answer 1 is {floors[-1]}")
+print(f"answer 2 is {floors.index(-1)}")

src/holt59/aoc/2015/day10.py

@@ -0,0 +1,148 @@
+import itertools
+import sys
+
+line = sys.stdin.read().strip()
+
+# see http://www.se16.info/js/lands2.htm for the explanation of 'atoms' (or elements)
+#
+# see also https://www.youtube.com/watch?v=ea7lJkEhytA (video link from AOC) and this
+# CodeGolf answer https://codegolf.stackexchange.com/a/8479/42148
+
+# fmt: off
+atoms = [
+    ("22", (0, )),  # 0
+    ("13112221133211322112211213322112", (71, 90, 0, 19, 2, )),  # 1
+    ("312211322212221121123222112", (1, )),  # 2
+    ("111312211312113221133211322112211213322112", (31, 19, 2, )),  # 3
+    ("1321132122211322212221121123222112", (3, )),  # 4
+    ("3113112211322112211213322112", (4, )),  # 5
+    ("111312212221121123222112", (5, )),  # 6
+    ("132112211213322112", (6, )),  # 7
+    ("31121123222112", (7, )),  # 8
+    ("111213322112", (8, )),  # 9
+    ("123222112", (9, )),  # 10
+    ("3113322112", (60, 10, )),  # 11
+    ("1113222112", (11, )),  # 12
+    ("1322112", (12, )),  # 13
+    ("311311222112", (66, 13, )),  # 14
+    ("1113122112", (14, )),  # 15
+    ("132112", (15, )),  # 16
+    ("3112", (16, )),  # 17
+    ("1112", (17, )),  # 18
+    ("12", (18, )),  # 19
+    ("3113112221133112", (66, 90, 0, 19, 26, )),  # 20
+    ("11131221131112", (20, )),  # 21
+    ("13211312", (21, )),  # 22
+    ("31132", (22, )),  # 23
+    ("111311222112", (23, 13, )),  # 24
+    ("13122112", (24, )),  # 25
+    ("32112", (25, )),  # 26
+    ("11133112", (29, 26, )),  # 27
+    ("131112", (27, )),  # 28
+    ("312", (28, )),  # 29
+    ("13221133122211332", (62, 19, 88, 0, 19, 29, )),  # 30
+    ("31131122211311122113222", (66, 30, )),  # 31
+    ("11131221131211322113322112", (31, 10, )),  # 32
+    ("13211321222113222112", (32, )),  # 33
+    ("3113112211322112", (33, )),  # 34
+    ("11131221222112", (34, )),  # 35
+    ("1321122112", (35, )),  # 36
+    ("3112112", (36, )),  # 37
+    ("1112133", (37, 91, )),  # 38
+    ("12322211331222113112211", (38, 0, 19, 42, )),  # 39
+    ("1113122113322113111221131221", (67, 39, )),  # 40
+    ("13211322211312113211", (40, )),  # 41
+    ("311322113212221", (41, )),  # 42
+    ("132211331222113112211", (62, 19, 42, )),  # 43
+    ("311311222113111221131221", (66, 43, )),  # 44
+    ("111312211312113211", (44, )),  # 45
+    ("132113212221", (45, )),  # 46
+    ("3113112211", (46, )),  # 47
+    ("11131221", (47, )),  # 48
+    ("13211", (48, )),  # 49
+    ("3112221", (60, 49, )),  # 50
+    ("1322113312211", (62, 19, 50, )),  # 51
+    ("311311222113111221", (66, 51, )),  # 52
+    ("11131221131211", (52, )),  # 53
+    ("13211321", (53, )),  # 54
+    ("311311", (54, )),  # 55
+    ("11131", (55, )),  # 56
+    ("1321133112", (56, 0, 19, 26, )),  # 57
+    ("31131112", (57, )),  # 58
+    ("111312", (58, )),  # 59
+    ("132", (59, )),  # 60
+    ("311332", (60, 19, 29, )),  # 61
+    ("1113222", (61, )),  # 62
+    ("13221133112", (62, 19, 26, )),  # 63
+    ("3113112221131112", (66, 63, )),  # 64
+    ("111312211312", (64, )),  # 65
+    ("1321132", (65, )),  # 66
+    ("311311222", (66, 60, )),  # 67
+    ("11131221133112", (67, 19, 26, )),  # 68
+    ("1321131112", (68, )),  # 69
+    ("311312", (69, )),  # 70
+    ("11132", (70, )),  # 71
+    ("13112221133211322112211213322113", (71, 90, 0, 19, 73, )),  # 72
+    ("312211322212221121123222113", (72, )),  # 73
+    ("111312211312113221133211322112211213322113", (31, 19, 73, )),  # 74
+    ("1321132122211322212221121123222113", (74, )),  # 75
+    ("3113112211322112211213322113", (75, )),  # 76
+    ("111312212221121123222113", (76, )),  # 77
+    ("132112211213322113", (77, )),  # 78
+    ("31121123222113", (78, )),  # 79
+    ("111213322113", (79, )),  # 80
+    ("123222113", (80, )),  # 81
+    ("3113322113", (60, 81, )),  # 82
+    ("1113222113", (82, )),  # 83
+    ("1322113", (83, )),  # 84
+    ("311311222113", (66, 84, )),  # 85
+    ("1113122113", (85, )),  # 86
+    ("132113", (86, )),  # 87
+    ("3113", (87, )),  # 88
+    ("1113", (88, )),  # 89
+    ("13", (89, )),  # 90
+    ("3", (90, )),  # 91
+]
+# fmt: on
+
+starters = [
+    "1",
+    "11",
+    "21",
+    "1211",
+    "111221",
+    "312211",
+    "13112221",
+    "1113213211",
+    "31131211131221",
+]
+
+
+def look_and_say_length(s: str, n: int) -> int:
+    if n == 0:
+        return len(s)
+
+    if s in starters:
+        return look_and_say_length(
+            "".join(f"{len(list(g))}{k}" for k, g in itertools.groupby(s)), n - 1
+        )
+
+    counts = {i: 0 for i in range(len(atoms))}
+    idx = next(i for i, (a, _) in enumerate(atoms) if s == a)
+    counts[idx] = 1
+
+    for _ in range(n):
+        c2 = {i: 0 for i in range(len(atoms))}
+        for i in counts:
+            for j in atoms[i][1]:
+                c2[j] += counts[i]
+        counts = c2
+
+    return sum(counts[i] * len(a[0]) for i, a in enumerate(atoms))
+
+
+answer_1 = look_and_say_length(line, 40)
+print(f"answer 1 is {answer_1}")
+
+answer_2 = look_and_say_length(line, 50)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day11.py

@@ -0,0 +1,49 @@
+import itertools
+import sys
+
+
+def is_valid(p: str) -> bool:
+    if any(c in "iol" for c in p):
+        return False
+
+    if not any(
+        ord(a) + 1 == ord(b) and ord(b) + 1 == ord(c)
+        for a, b, c in zip(p, p[1:], p[2:])
+    ):
+        return False
+
+    if sum(len(list(g)) >= 2 for _, g in itertools.groupby(p)) < 2:
+        return False
+
+    return True
+
+
+assert not is_valid("hijklmmn")
+assert not is_valid("abbceffg")
+assert not is_valid("abbcegjk")
+assert is_valid("abcdffaa")
+assert is_valid("ghjaabcc")
+
+
+def increment(p: str) -> str:
+    if p[-1] == "z":
+        return increment(p[:-1]) + "a"
+    elif p[-1] in "iol":
+        return p[:-1] + chr(ord(p[-1]) + 2)
+    else:
+        return p[:-1] + chr(ord(p[-1]) + 1)
+
+
+def find_next_password(p: str) -> str:
+    while not is_valid(p):
+        p = increment(p)
+    return p
+
+
+line = sys.stdin.read().strip()
+
+answer_1 = find_next_password(line)
+print(f"answer 1 is {answer_1}")
+
+answer_2 = find_next_password(increment(answer_1))
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day12.py

@@ -0,0 +1,27 @@
+import json
+import sys
+from typing import TypeAlias
+
+JsonObject: TypeAlias = dict[str, "JsonObject"] | list["JsonObject"] | int | str
+
+
+def json_sum(value: JsonObject, ignore: str | None = None) -> int:
+    if isinstance(value, str):
+        return 0
+    elif isinstance(value, int):
+        return value
+    elif isinstance(value, list):
+        return sum(json_sum(v, ignore=ignore) for v in value)
+    elif ignore not in value.values():
+        return sum(json_sum(v, ignore=ignore) for v in value.values())
+    else:
+        return 0
+
+
+data: JsonObject = json.load(sys.stdin)
+
+answer_1 = json_sum(data)
+print(f"answer 1 is {answer_1}")
+
+answer_2 = json_sum(data, "red")
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day13.py

@@ -0,0 +1,41 @@
+import itertools
+import sys
+from collections import defaultdict
+from typing import Literal, cast
+
+import parse  # type: ignore
+
+
+def max_change_in_happiness(happiness: dict[str, dict[str, int]]) -> int:
+    guests = list(happiness)
+    return max(
+        sum(
+            happiness[o][d] + happiness[d][o]
+            for o, d in zip((guests[0],) + order, order + (guests[0],))
+        )
+        for order in map(tuple, itertools.permutations(guests[1:]))
+    )
+
+
+lines = sys.stdin.read().splitlines()
+
+happiness: dict[str, dict[str, int]] = defaultdict(dict)
+for line in lines:
+    u1, gain_or_loose, hap, u2 = cast(
+        tuple[str, Literal["gain", "lose"], int, str],
+        parse.parse(  # type: ignore
+            "{} would {} {:d} happiness units by sitting next to {}.", line
+        ),
+    )
+    happiness[u1][u2] = hap if gain_or_loose == "gain" else -hap
+
+
+answer_1 = max_change_in_happiness(happiness)
+print(f"answer 1 is {answer_1}")
+
+for guest in list(happiness):
+    happiness["me"][guest] = 0
+    happiness[guest]["me"] = 0
+
+answer_2 = max_change_in_happiness(happiness)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day14.py

@@ -0,0 +1,62 @@
+import sys
+from dataclasses import dataclass
+from typing import Literal, cast
+
+import parse  # type: ignore
+
+
+@dataclass(frozen=True)
+class Reindeer:
+    name: str
+    speed: int
+    fly_time: int
+    rest_time: int
+
+
+lines = sys.stdin.read().splitlines()
+
+reindeers: list[Reindeer] = []
+for line in lines:
+    reindeer, speed, speed_time, rest_time = cast(
+        tuple[str, int, int, int],
+        parse.parse(  # type: ignore
+            "{} can fly {:d} km/s for {:d} seconds, "
+            "but then must rest for {:d} seconds.",
+            line,
+        ),
+    )
+    reindeers.append(
+        Reindeer(name=reindeer, speed=speed, fly_time=speed_time, rest_time=rest_time)
+    )
+
+target = 1000 if len(reindeers) <= 2 else 2503
+
+states: dict[Reindeer, tuple[Literal["resting", "flying"], int]] = {
+    reindeer: ("resting", 0) for reindeer in reindeers
+}
+distances: dict[Reindeer, int] = {reindeer: 0 for reindeer in reindeers}
+points: dict[Reindeer, int] = {reindeer: 0 for reindeer in reindeers}
+
+for time in range(target):
+    for reindeer in reindeers:
+        if states[reindeer][0] == "flying":
+            distances[reindeer] += reindeer.speed
+
+    top_distance = max(distances.values())
+    for reindeer in reindeers:
+        if distances[reindeer] == top_distance:
+            points[reindeer] += 1
+
+    for reindeer in reindeers:
+        if states[reindeer][1] == time:
+            if states[reindeer][0] == "resting":
+                states[reindeer] = ("flying", time + reindeer.fly_time)
+            else:
+                states[reindeer] = ("resting", time + reindeer.rest_time)
+
+
+answer_1 = max(distances.values())
+print(f"answer 1 is {answer_1}")
+
+answer_2 = max(points.values()) - 1
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day15.py

@@ -0,0 +1,57 @@
+import math
+import sys
+from typing import Sequence, cast
+
+import parse  # type: ignore
+
+
+def score(ingredients: list[list[int]], teaspoons: Sequence[int]) -> int:
+    return math.prod(
+        max(
+            0,
+            sum(
+                ingredient[prop] * teaspoon
+                for ingredient, teaspoon in zip(ingredients, teaspoons)
+            ),
+        )
+        for prop in range(len(ingredients[0]) - 1)
+    )
+
+
+lines = sys.stdin.read().splitlines()
+
+ingredients: list[list[int]] = []
+for line in lines:
+    _, *scores = cast(
+        tuple[str, int, int, int, int, int],
+        parse.parse(  # type: ignore
+            "{}: capacity {:d}, durability {:d}, flavor {:d}, "
+            "texture {:d}, calories {:d}",
+            line,
+        ),
+    )
+    ingredients.append(scores)
+
+total_teaspoons = 100
+calories: list[int] = []
+scores: list[int] = []
+
+for a in range(total_teaspoons + 1):
+    for b in range(total_teaspoons + 1 - a):
+        for c in range(total_teaspoons + 1 - a - b):
+            teaspoons = (a, b, c, total_teaspoons - a - b - c)
+
+            scores.append(score(ingredients, teaspoons))
+            calories.append(
+                sum(
+                    ingredient[-1] * teaspoon
+                    for ingredient, teaspoon in zip(ingredients, teaspoons)
+                )
+            )
+
+
+answer_1 = max(scores)
+print(f"answer 1 is {answer_1}")
+
+answer_2 = max(score for score, calory in zip(scores, calories) if calory == 500)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day16.py

@@ -0,0 +1,51 @@
+import operator as op
+import re
+import sys
+from collections import defaultdict
+from typing import Callable
+
+MFCSAM: dict[str, int] = {
+    "children": 3,
+    "cats": 7,
+    "samoyeds": 2,
+    "pomeranians": 3,
+    "akitas": 0,
+    "vizslas": 0,
+    "goldfish": 5,
+    "trees": 3,
+    "cars": 2,
+    "perfumes": 1,
+}
+
+lines = sys.stdin.readlines()
+
+aunts: list[dict[str, int]] = [
+    {
+        match[1]: int(match[2])
+        for match in re.findall(R"((?P<compound>[^:, ]+): (?P<quantity>\d+))", line)
+    }
+    for line in lines
+]
+
+
+def match(operators: dict[str, Callable[[int, int], bool]]) -> int:
+    return next(
+        i
+        for i, aunt in enumerate(aunts, start=1)
+        if all(operators[k](aunt[k], MFCSAM[k]) for k in aunt)
+    )
+
+
+answer_1 = match(defaultdict(lambda: op.eq))
+print(f"answer 1 is {answer_1}")
+
+answer_2 = match(
+    defaultdict(
+        lambda: op.eq,
+        trees=op.gt,
+        cats=op.gt,
+        pomeranians=op.lt,
+        goldfish=op.lt,
+    )
+)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day17.py

@@ -0,0 +1,30 @@
+import sys
+from typing import Iterator
+
+
+def iter_combinations(value: int, containers: list[int]) -> Iterator[tuple[int, ...]]:
+    if value < 0:
+        return
+
+    if value == 0:
+        yield ()
+
+    for i in range(len(containers)):
+        for combination in iter_combinations(
+            value - containers[i], containers[i + 1 :]
+        ):
+            yield (containers[i],) + combination
+
+
+containers = [int(c) for c in sys.stdin.read().split()]
+total = 25 if len(containers) <= 5 else 150
+
+combinations = [combination for combination in iter_combinations(total, containers)]
+
+answer_1 = len(combinations)
+print(f"answer 1 is {answer_1}")
+
+min_containers = min(len(combination) for combination in combinations)
+
+answer_2 = sum(1 for combination in combinations if len(combination) == min_containers)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day18.py

@@ -0,0 +1,66 @@
+import itertools
+import sys
+
+import numpy as np
+from numpy.typing import NDArray
+
+grid0 = np.array([[c == "#" for c in line] for line in sys.stdin.read().splitlines()])
+
+# add an always off circle around
+grid0 = np.concatenate(
+    [
+        np.zeros((grid0.shape[0] + 2, 1), dtype=bool),
+        np.concatenate(
+            [
+                np.zeros((1, grid0.shape[1]), dtype=bool),
+                grid0,
+                np.zeros((1, grid0.shape[1]), dtype=bool),
+            ]
+        ),
+        np.zeros((grid0.shape[0] + 2, 1), dtype=bool),
+    ],
+    axis=1,
+)
+
+moves = list(itertools.product([-1, 0, 1], repeat=2))
+moves.remove((0, 0))
+
+jjs, iis = np.meshgrid(
+    np.arange(1, grid0.shape[0] - 1, dtype=int),
+    np.arange(1, grid0.shape[1] - 1, dtype=int),
+)
+iis, jjs = iis.flatten(), jjs.flatten()
+
+ins = iis[:, None] + np.array(moves)[:, 0]
+jns = jjs[:, None] + np.array(moves)[:, 1]
+
+
+def game_of_life(grid: NDArray[np.bool_]) -> NDArray[np.bool_]:
+    neighbors_on = grid[ins, jns].sum(axis=1)
+    cells_on = grid[iis, jjs]
+
+    grid = np.zeros_like(grid)
+    grid[iis, jjs] = (neighbors_on == 3) | (cells_on & (neighbors_on == 2))
+
+    return grid
+
+
+grid = grid0
+n_steps = 4 if len(grid) < 10 else 100
+for _ in range(n_steps):
+    grid = game_of_life(grid)
+
+answer_1 = grid.sum()
+print(f"answer 1 is {answer_1}")
+
+
+n_steps = 5 if len(grid) < 10 else 100
+grid = grid0
+for _ in range(n_steps):
+    grid[[1, 1, -2, -2], [1, -2, 1, -2]] = True
+    grid = game_of_life(grid)
+
+grid[[1, 1, -2, -2], [1, -2, 1, -2]] = True
+
+answer_2 = sum(cell for line in grid for cell in line)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day19.py

@@ -0,0 +1,56 @@
+import sys
+from collections import defaultdict
+
+replacements_s, molecule = sys.stdin.read().split("\n\n")
+
+REPLACEMENTS: dict[str, list[str]] = defaultdict(list)
+for replacement_s in replacements_s.splitlines():
+    p = replacement_s.split(" => ")
+    REPLACEMENTS[p[0]].append(p[1])
+molecule = molecule.strip()
+
+generated = [
+    molecule[:i] + replacement + molecule[i + len(symbol) :]
+    for symbol, replacements in REPLACEMENTS.items()
+    for replacement in replacements
+    for i in range(len(molecule))
+    if molecule[i:].startswith(symbol)
+]
+
+answer_1 = len(set(generated))
+print(f"answer 1 is {answer_1}")
+
+inversion: dict[str, str] = {
+    replacement: symbol
+    for symbol, replacements in REPLACEMENTS.items()
+    for replacement in replacements
+}
+
+# there is actually only one way to create the molecule, and we can greedily replace
+# tokens with their replacements, e.g., if H => OH then we can replace OH by H directly
+# without thinking
+
+count = 0
+while molecule != "e":
+    i = 0
+    m2 = ""
+    while i < len(molecule):
+        found = False
+        for replacement in inversion:
+            if molecule[i:].startswith(replacement):
+                m2 += inversion[replacement]
+                i += len(replacement)
+                count += 1
+                found = True
+                break
+
+        if not found:
+            m2 += molecule[i]
+            i += 1
+
+    # print(m2)
+    molecule = m2
+
+
+answer_2 = count
+print(f"answer 2 is {count}")

src/holt59/aoc/2015/day2.py

@@ -0,0 +1,20 @@
+import sys
+
+import numpy as np
+
+lines = sys.stdin.read().splitlines()
+
+length, width, height = np.array(
+    [[int(c) for c in line.split("x")] for line in lines]
+).T
+
+lw, wh, hl = (length * width, width * height, height * length)
+
+answer_1 = np.sum(2 * (lw + wh + hl) + np.min(np.stack([lw, wh, hl]), axis=0))
+print(f"answer 1 is {answer_1}")
+
+answer_2 = np.sum(
+    length * width * height
+    + 2 * np.min(np.stack([length + width, length + height, height + width]), axis=0)
+)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day20.py

@@ -0,0 +1,28 @@
+import itertools
+import sys
+
+target = int(sys.stdin.read())
+
+
+def presents(n: int, elf: int, max: int = target) -> int:
+    count = 0
+    k = 1
+    while k * k < n:
+        if n % k == 0:
+            if n // k <= max:
+                count += elf * k
+            if k <= max:
+                count += elf * (n // k)
+        k += 1
+
+    if k * k == n and k <= max:
+        count += elf * k
+
+    return count
+
+
+answer_1 = next(n for n in itertools.count(1) if presents(n, 10) >= target)
+print(f"answer 1 is {answer_1}")
+
+answer_2 = next(n for n in itertools.count(1) if presents(n, 11, 50) >= target)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day21.py

@@ -0,0 +1,66 @@
+import itertools
+import sys
+from math import ceil
+from typing import TypeAlias
+
+Modifier: TypeAlias = tuple[str, int, int, int]
+
+WEAPONS: list[Modifier] = [
+    ("Dagger", 8, 4, 0),
+    ("Shortsword", 10, 5, 0),
+    ("Warhammer", 25, 6, 0),
+    ("Longsword", 40, 7, 0),
+    ("Greataxe", 74, 8, 0),
+]
+
+ARMORS: list[Modifier] = [
+    ("", 0, 0, 0),
+    ("Leather", 13, 0, 1),
+    ("Chainmail", 31, 0, 2),
+    ("Splintmail", 53, 0, 3),
+    ("Bandedmail", 75, 0, 4),
+    ("Platemail", 102, 0, 5),
+]
+
+RINGS: list[Modifier] = [
+    ("", 0, 0, 0),
+    ("Damage +1", 25, 1, 0),
+    ("Damage +2", 50, 2, 0),
+    ("Damage +3", 100, 3, 0),
+    ("Defense +1", 20, 0, 1),
+    ("Defense +2", 40, 0, 2),
+    ("Defense +3", 80, 0, 3),
+]
+
+
+lines = sys.stdin.read().splitlines()
+
+player_hp = 100
+
+boss_attack = int(lines[1].split(":")[1].strip())
+boss_armor = int(lines[2].split(":")[1].strip())
+boss_hp = int(lines[0].split(":")[1].strip())
+
+
+min_cost, max_cost = 1_000_000, 0
+for equipments in itertools.product(WEAPONS, ARMORS, RINGS, RINGS):
+    if equipments[-1][0] != "" and equipments[-2] == equipments[-1]:
+        continue
+
+    cost, player_attack, player_armor = (
+        sum(equipment[1:][k] for equipment in equipments) for k in range(3)
+    )
+
+    if ceil(boss_hp / max(1, player_attack - boss_armor)) <= ceil(
+        player_hp / max(1, boss_attack - player_armor)
+    ):
+        min_cost = min(cost, min_cost)
+    else:
+        max_cost = max(cost, max_cost)
+
+
+answer_1 = min_cost
+print(f"answer 1 is {answer_1}")
+
+answer_2 = max_cost
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day3.py

@@ -0,0 +1,34 @@
+import sys
+from collections import defaultdict
+
+line = sys.stdin.read().strip()
+
+
+def process(directions: str) -> dict[tuple[int, int], int]:
+    counts: dict[tuple[int, int], int] = defaultdict(lambda: 0)
+    counts[0, 0] = 1
+    x, y = (0, 0)
+
+    for c in directions:
+        match c:
+            case ">":
+                x += 1
+            case "<":
+                x -= 1
+            case "^":
+                y -= 1
+            case "v":
+                y += 1
+            case _:
+                raise ValueError()
+
+        counts[x, y] += 1
+
+    return counts
+
+
+answer_1 = len(process(line))
+print(f"answer 1 is {answer_1}")
+
+answer_2 = len(process(line[::2]) | process(line[1::2]))
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day4.py

@@ -0,0 +1,16 @@
+import hashlib
+import itertools
+import sys
+
+line = sys.stdin.read().strip()
+
+it = iter(itertools.count(1))
+answer_1 = next(
+    i for i in it if hashlib.md5(f"{line}{i}".encode()).hexdigest().startswith("00000")
+)
+print(f"answer 1 is {answer_1}")
+
+answer_2 = next(
+    i for i in it if hashlib.md5(f"{line}{i}".encode()).hexdigest().startswith("000000")
+)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day5.py

@@ -0,0 +1,36 @@
+import sys
+
+VOWELS = "aeiou"
+FORBIDDEN = {"ab", "cd", "pq", "xy"}
+
+
+def is_nice_1(s: str) -> bool:
+    if sum(c in VOWELS for c in s) < 3:
+        return False
+
+    if not any(a == b for a, b in zip(s[:-1:], s[1::])):
+        return False
+
+    if any(s.find(f) >= 0 for f in FORBIDDEN):
+        return False
+
+    return True
+
+
+def is_nice_2(s: str) -> bool:
+    if not any(s.find(s[i : i + 2], i + 2) >= 0 for i in range(len(s))):
+        return False
+
+    if not any(a == b for a, b in zip(s[:-1:], s[2::])):
+        return False
+
+    return True
+
+
+lines = sys.stdin.read().splitlines()
+
+answer_1 = sum(map(is_nice_1, lines))
+print(f"answer 1 is {answer_1}")
+
+answer_2 = sum(map(is_nice_2, lines))
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day6.py

@@ -0,0 +1,33 @@
+import sys
+from typing import Literal, cast
+
+import numpy as np
+import parse  # type: ignore
+
+lines = sys.stdin.read().splitlines()
+
+lights_1 = np.zeros((1000, 1000), dtype=bool)
+lights_2 = np.zeros((1000, 1000), dtype=int)
+for line in lines:
+    action, sx, sy, ex, ey = cast(
+        tuple[Literal["turn on", "turn off", "toggle"], int, int, int, int],
+        parse.parse("{} {:d},{:d} through {:d},{:d}", line),  # type: ignore
+    )
+    ex, ey = ex + 1, ey + 1
+
+    match action:
+        case "turn on":
+            lights_1[sx:ex, sy:ey] = True
+            lights_2[sx:ex, sy:ey] += 1
+        case "turn off":
+            lights_1[sx:ex, sy:ey] = False
+            lights_2[sx:ex, sy:ey] = np.maximum(lights_2[sx:ex, sy:ey] - 1, 0)
+        case "toggle":
+            lights_1[sx:ex, sy:ey] = ~lights_1[sx:ex, sy:ey]
+            lights_2[sx:ex, sy:ey] += 2
+
+answer_1 = lights_1.sum()
+print(f"answer 1 is {answer_1}")
+
+answer_2 = lights_2.sum()
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day7.py

@@ -0,0 +1,101 @@
+import logging
+import operator
+import os
+import sys
+from typing import Callable
+
+VERBOSE = os.getenv("AOC_VERBOSE") == "True"
+logging.basicConfig(level=logging.INFO if VERBOSE else logging.WARNING)
+
+OPERATORS = {
+    "AND": operator.and_,
+    "OR": operator.or_,
+    "LSHIFT": operator.lshift,
+    "RSHIFT": operator.rshift,
+}
+
+ValueGetter = Callable[[dict[str, int]], int]
+Signals = dict[
+    str,
+    tuple[
+        tuple[str, str],
+        tuple[ValueGetter, ValueGetter],
+        Callable[[int, int], int],
+    ],
+]
+
+
+def zero_op(_a: int, _b: int) -> int:
+    return 0
+
+
+def value_of(key: str) -> tuple[str, Callable[[dict[str, int]], int]]:
+    try:
+        return "", lambda _p, _v=int(key): _v
+    except ValueError:
+        return key, lambda values: values[key]
+
+
+lines = sys.stdin.read().splitlines()
+
+signals: Signals = {}
+values: dict[str, int] = {"": 0}
+
+for line in lines:
+    command, signal = line.split(" -> ")
+
+    if command.startswith("NOT"):
+        name = command.split(" ")[1]
+        signals[signal] = (
+            (name, ""),
+            (lambda values, _n=name: values[_n], lambda _v: 0),
+            lambda a, _b: ~a,
+        )
+
+    elif not any(command.find(name) >= 0 for name in OPERATORS):
+        try:
+            values[signal] = int(command)
+        except ValueError:
+            signals[signal] = (
+                (command, ""),
+                (lambda values, _c=command: values[_c], lambda _v: 0),
+                lambda a, _b: a,
+            )
+
+    else:
+        op: Callable[[int, int], int] = zero_op
+        lhs_s, rhs_s = "", ""
+
+        for name in OPERATORS:
+            if command.find(name) >= 0:
+                op = OPERATORS[name]
+                lhs_s, rhs_s = command.split(f" {name} ")
+                break
+
+        lhs_s, lhs_fn = value_of(lhs_s)
+        rhs_s, rhs_fn = value_of(rhs_s)
+
+        signals[signal] = ((lhs_s, rhs_s), (lhs_fn, rhs_fn), op)
+
+
+def process(
+    signals: Signals,
+    values: dict[str, int],
+) -> dict[str, int]:
+    while signals:
+        signal = next(s for s in signals if all(p in values for p in signals[s][0]))
+        _, deps, command = signals[signal]
+        values[signal] = command(deps[0](values), deps[1](values)) % 65536
+        del signals[signal]
+
+    return values
+
+
+values_1 = process(signals.copy(), values.copy())
+logging.info("\n" + "\n".join(f"{k}: {values_1[k]}" for k in sorted(values_1)))
+answer_1 = values_1["a"]
+print(f"answer 1 is {answer_1}")
+
+values_2 = process(signals.copy(), values | {"b": values_1["a"]})
+answer_2 = values_2["a"]
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day8.py

@@ -0,0 +1,35 @@
+import logging
+import os
+import sys
+
+VERBOSE = os.getenv("AOC_VERBOSE") == "True"
+logging.basicConfig(level=logging.INFO if VERBOSE else logging.WARNING)
+
+
+lines = sys.stdin.read().splitlines()
+
+answer_1 = sum(
+    # left and right quotes (not in memory)
+    2
+    # each \\ adds one character in the literals (compared to memory)
+    + line.count(R"\\")
+    # each \" adds one character in the literals (compared to memory)
+    + line[1:-1].count(R"\"")
+    # each \xFF adds 3 characters in the literals (compared to memory), but we must not
+    # count A\\x (A != \), but we must count A\\\x (A != \) - in practice we should also
+    # avoid \\\\x, etc., but this does not occur in the examples and the actual input
+    + 3 * (line.count(R"\x") - line.count(R"\\x") + line.count(R"\\\x"))
+    for line in lines
+)
+print(f"answer 1 is {answer_1}")
+
+answer_2 = sum(
+    # needs to wrap in quotes (2 characters)
+    2
+    # needs to escape every \ with an extra \
+    + line.count("\\")
+    # needs to escape every " with an extra \ (including the first and last ones)
+    + line.count('"')
+    for line in lines
+)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2015/day9.py

@@ -0,0 +1,26 @@
+import itertools
+import sys
+from collections import defaultdict
+from typing import cast
+
+import parse  # type: ignore
+
+lines = sys.stdin.read().splitlines()
+
+distances: dict[str, dict[str, int]] = defaultdict(dict)
+for line in lines:
+    origin, destination, length = cast(
+        tuple[str, str, int], parse.parse("{} to {} = {:d}", line)  # type: ignore
+    )
+    distances[origin][destination] = distances[destination][origin] = length
+
+distance_of_routes = {
+    route: sum(distances[o][d] for o, d in zip(route[:-1], route[1:]))
+    for route in map(tuple, itertools.permutations(distances))
+}
+
+answer_1 = min(distance_of_routes.values())
+print(f"answer 1 is {answer_1}")
+
+answer_2 = max(distance_of_routes.values())
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day1.py

@@ -0,0 +1,14 @@
+import sys
+
+lines = sys.stdin.read().splitlines()
+
+values = [int(line) for line in lines]
+
+# part 1
+answer_1 = sum(v2 > v1 for v1, v2 in zip(values[:-1], values[1:]))
+print(f"answer 1 is {answer_1}")
+
+# part 2
+runnings = [sum(values[i : i + 3]) for i in range(len(values) - 2)]
+answer_2 = sum(v2 > v1 for v1, v2 in zip(runnings[:-1], runnings[1:]))
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day10.py

@@ -0,0 +1,13 @@
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+answer_1 = ...
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day11.py

@@ -0,0 +1,13 @@
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+answer_1 = ...
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day12.py

@@ -0,0 +1,13 @@
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+answer_1 = ...
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day13.py

@@ -0,0 +1,13 @@
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+answer_1 = ...
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day14.py

@@ -0,0 +1,13 @@
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+answer_1 = ...
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day15.py

@@ -0,0 +1,13 @@
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+answer_1 = ...
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day16.py

@@ -0,0 +1,13 @@
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+answer_1 = ...
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day17.py

@@ -0,0 +1,13 @@
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+answer_1 = ...
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day18.py

@@ -0,0 +1,13 @@
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+answer_1 = ...
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day19.py

@@ -0,0 +1,13 @@
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+answer_1 = ...
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day2.py

@@ -0,0 +1,40 @@
+import sys
+from math import prod
+from typing import Literal, cast
+
+lines = sys.stdin.read().splitlines()
+
+commands = [
+    (cast(Literal["forward", "up", "down"], (p := line.split())[0]), int(p[1]))
+    for line in lines
+]
+
+
+def depth_and_position(use_aim: bool):
+    aim, pos, depth = 0, 0, 0
+    for command, value in commands:
+        d_depth = 0
+        match command:
+            case "forward":
+                pos += value
+                depth += value * aim
+            case "up":
+                d_depth = -value
+            case "down":
+                d_depth = value
+
+        if use_aim:
+            aim += d_depth
+        else:
+            depth += value
+
+    return depth, pos
+
+
+# part 1
+answer_1 = prod(depth_and_position(False))
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = prod(depth_and_position(True))
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day20.py

@@ -0,0 +1,13 @@
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+answer_1 = ...
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day21.py

@@ -0,0 +1,13 @@
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+answer_1 = ...
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day22.py

@@ -0,0 +1,13 @@
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+answer_1 = ...
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day23.py

@@ -0,0 +1,13 @@
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+answer_1 = ...
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day24.py

@@ -0,0 +1,13 @@
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+answer_1 = ...
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day25.py

@@ -0,0 +1,13 @@
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+answer_1 = ...
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day3.py

@@ -0,0 +1,39 @@
+import sys
+from collections import Counter
+from typing import Literal
+
+
+def generator_rating(
+    values: list[str], most_common: bool, default: Literal["0", "1"]
+) -> str:
+    index = 0
+    most_common_idx = 0 if most_common else 1
+
+    while len(values) > 1:
+        cnt = Counter(value[index] for value in values)
+        bit = cnt.most_common(2)[most_common_idx][0]
+        if cnt["0"] == cnt["1"]:
+            bit = default
+        values = [value for value in values if value[index] == bit]
+        index += 1
+
+    return values[0]
+
+
+lines = sys.stdin.read().splitlines()
+
+
+# part 1
+most_and_least_common = [
+    tuple(Counter(line[col] for line in lines).most_common(2)[m][0] for m in range(2))
+    for col in range(len(lines[0]))
+]
+gamma_rate = int("".join(most for most, _ in most_and_least_common), base=2)
+epsilon_rate = int("".join(least for _, least in most_and_least_common), base=2)
+print(f"answer 1 is {gamma_rate * epsilon_rate}")
+
+# part 2
+oxygen_generator_rating = int(generator_rating(lines, True, "1"), base=2)
+co2_scrubber_rating = int(generator_rating(lines, False, "0"), base=2)
+answer_2 = oxygen_generator_rating * co2_scrubber_rating
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day4.py

@@ -0,0 +1,45 @@
+import sys
+
+import numpy as np
+
+lines = sys.stdin.read().splitlines()
+
+numbers = [int(c) for c in lines[0].split(",")]
+
+boards = np.asarray(
+    [
+        [[int(c) for c in line.split()] for line in lines[start : start + 5]]
+        for start in range(2, len(lines), 6)
+    ]
+)
+
+# (round, score) for each board (-1 when not found)
+winning_rounds: list[tuple[int, int]] = [(-1, -1) for _ in range(len(boards))]
+marked = np.zeros_like(boards, dtype=bool)
+
+for round, number in enumerate(numbers):
+    # mark boards
+    marked[boards == number] = True
+
+    # check each board for winning
+    for index in range(len(boards)):
+        if winning_rounds[index][0] > 0:
+            continue
+
+        if np.any(np.all(marked[index], axis=0) | np.all(marked[index], axis=1)):
+            winning_rounds[index] = (
+                round,
+                number * int(np.sum(boards[index][~marked[index]])),
+            )
+
+    # all boards are winning - break
+    if np.all(marked.all(axis=1) | marked.all(axis=2)):
+        break
+
+# part 1
+(_, score) = min(winning_rounds, key=lambda w: w[0])
+print(f"answer 1 is {score}")
+
+# part 2
+(_, score) = max(winning_rounds, key=lambda w: w[0])
+print(f"answer 2 is {score}")

src/holt59/aoc/2021/day5.py

@@ -1,7 +1,4 @@
-# -*- encoding: utf-8 -*-
-
 import sys
-from collections import defaultdict
 
 import numpy as np
 
@@ -34,7 +31,6 @@ counts_1 = np.zeros((y_max + 1, x_max + 1), dtype=int)
 counts_2 = counts_1.copy()
 
 for (x1, y1), (x2, y2) in sections:
-
     x_rng = range(x1, x2 + 1, 1) if x2 >= x1 else range(x1, x2 - 1, -1)
     y_rng = range(y1, y2 + 1, 1) if y2 >= y1 else range(y1, y2 - 1, -1)
 

src/holt59/aoc/2021/day6.py

@@ -0,0 +1,21 @@
+import sys
+
+values = [int(c) for c in sys.stdin.read().strip().split(",")]
+
+days = 256
+lanterns = {day: 0 for day in range(days)}
+for value in values:
+    for day in range(value, days, 7):
+        lanterns[day] += 1
+
+for day in range(days):
+    for day2 in range(day + 9, days, 7):
+        lanterns[day2] += lanterns[day]
+
+# part 1
+answer_1 = sum(v for k, v in lanterns.items() if k < 80) + len(values)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = sum(lanterns.values()) + len(values)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day7.py

@@ -0,0 +1,21 @@
+import sys
+
+import numpy as np
+
+positions = np.asarray([int(c) for c in sys.stdin.read().strip().split(",")])
+
+min_position, max_position = positions.min(), positions.max()
+
+# part 1
+answer_1 = min(
+    np.sum(np.abs(positions - position))
+    for position in range(min_position, max_position + 1)
+)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = min(
+    np.sum(abs(positions - position) * (abs(positions - position) + 1) // 2)
+    for position in range(min_position, max_position + 1)
+)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day8.py

@@ -0,0 +1,87 @@
+import itertools
+import os
+import sys
+
+VERBOSE = os.getenv("AOC_VERBOSE") == "True"
+
+digits = {
+    "abcefg": 0,
+    "cf": 1,
+    "acdeg": 2,
+    "acdfg": 3,
+    "bcdf": 4,
+    "abdfg": 5,
+    "abdefg": 6,
+    "acf": 7,
+    "abcdefg": 8,
+    "abcdfg": 9,
+}
+
+lines = sys.stdin.read().splitlines()
+
+# part 1
+lengths = {len(k) for k, v in digits.items() if v in (1, 4, 7, 8)}
+answer_1 = sum(
+    len(p) in lengths for line in lines for p in line.split("|")[1].strip().split()
+)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+values: list[int] = []
+
+for line in lines:
+    parts = line.split("|")
+    broken_digits = sorted(parts[0].strip().split(), key=len)
+
+    per_length = {
+        k: list(v)
+        for k, v in itertools.groupby(sorted(broken_digits, key=len), key=len)
+    }
+
+    # a can be found immediately
+    a = next(u for u in per_length[3][0] if u not in per_length[2][0])
+
+    # c and f have only two possible values corresponding to the single entry of
+    # length 2
+    cf = list(per_length[2][0])
+
+    # the only digit of length 4 contains bcdf, so we can deduce bd by removing cf
+    bd = [u for u in per_length[4][0] if u not in cf]
+
+    # the 3 digits of length 5 have a, d and g in common
+    adg = [u for u in per_length[5][0] if all(u in pe for pe in per_length[5][1:])]
+
+    # we can remove a
+    dg = [u for u in adg if u != a]
+
+    # we can deduce d and g
+    d = next(u for u in dg if u in bd)
+    g = next(u for u in dg if u != d)
+
+    # then b
+    b = next(u for u in bd if u != d)
+
+    # f is in the three 6-length digits, while c is only in 2
+    f = next(u for u in cf if all(u in p for p in per_length[6]))
+
+    # c is not f
+    c = next(u for u in cf if u != f)
+
+    # e is the last one
+    e = next(u for u in "abcdefg" if u not in {a, b, c, d, f, g})
+
+    mapping = dict(zip((a, b, c, d, e, f, g), "abcdefg"))
+
+    value = 0
+    for number in parts[1].strip().split():
+        digit = "".join(sorted(mapping[c] for c in number))
+        value = 10 * value + digits[digit]
+
+    if VERBOSE:
+        print(value)
+
+    values.append(value)
+
+
+answer_2 = sum(values)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2021/day9.py

@@ -0,0 +1,44 @@
+import sys
+from math import prod
+
+values = [[int(c) for c in row] for row in sys.stdin.read().splitlines()]
+n_rows, n_cols = len(values), len(values[0])
+
+
+def neighbors(point: tuple[int, int]):
+    i, j = point
+    for di, dj in ((-1, 0), (+1, 0), (0, -1), (0, +1)):
+        if 0 <= i + di < n_rows and 0 <= j + dj < n_cols:
+            yield (i + di, j + dj)
+
+
+def basin(start: tuple[int, int]) -> set[tuple[int, int]]:
+    visited: set[tuple[int, int]] = set()
+    queue = [start]
+
+    while queue:
+        i, j = queue.pop()
+
+        if (i, j) in visited or values[i][j] == 9:
+            continue
+
+        visited.add((i, j))
+        queue.extend(neighbors((i, j)))
+
+    return visited
+
+
+low_points = [
+    (i, j)
+    for i in range(n_rows)
+    for j in range(n_cols)
+    if all(values[ti][tj] > values[i][j] for ti, tj in neighbors((i, j)))
+]
+
+# part 1
+answer_1 = sum(values[i][j] + 1 for i, j in low_points)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = prod(sorted(len(basin(point)) for point in low_points)[-3:])
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2022/day1.py

@@ -0,0 +1,7 @@
+import sys
+
+blocks = sys.stdin.read().split("\n\n")
+values = sorted(sum(map(int, block.split())) for block in blocks)
+
+print(f"answer 1 is {values[-1]}")
+print(f"answer 2 is {sum(values[-3:])}")

src/holt59/aoc/2022/day10.py

@@ -1,5 +1,3 @@
-# -*- encoding: utf-8 -*-
-
 import sys
 
 lines = sys.stdin.read().splitlines()

src/holt59/aoc/2022/day11.py

@@ -1,5 +1,3 @@
-# -*- encoding: utf-8 -*-
-
 import copy
 import sys
 from functools import reduce
@@ -7,7 +5,6 @@ from typing import Callable, Final, Mapping, Sequence
 
 
 class Monkey:
-
     id: Final[int]
     items: Final[Sequence[int]]
     worry_fn: Final[Callable[[int], int]]
@@ -97,8 +94,7 @@ def run(
     # number of inspects
     inspects = {monkey: 0 for monkey in monkeys}
 
-    for round in range(n_rounds):
-
+    for _ in range(n_rounds):
         for monkey in monkeys:
             for item in items[monkey]:
                 inspects[monkey] += 1

src/holt59/aoc/2022/day12.py

@@ -1,5 +1,3 @@
-# -*- encoding: utf-8 -*-
-
 import heapq
 import sys
 from typing import Callable, Iterator, TypeVar
@@ -44,7 +42,6 @@ def dijkstra(
         visited.add(current)
 
         for neighbor in neighbors(current):
-
             if neighbor in visited:
                 continue
 
@@ -60,7 +57,6 @@ def dijkstra(
 
 
 def make_path(parents: dict[Node, Node], start: Node, end: Node) -> list[Node] | None:
-
     if end not in parents:
         return None
 
@@ -109,7 +105,6 @@ def neighbors(
         (c_row, c_col - 1),
         (c_row, c_col + 1),
     ):
-
         if not (n_row >= 0 and n_row < n_rows and n_col >= 0 and n_col < n_cols):
             continue
 

src/holt59/aoc/2022/day13.py

@@ -1,27 +1,27 @@
-# -*- encoding: utf-8 -*-
-
 import json
 import sys
 from functools import cmp_to_key
+from typing import TypeAlias, cast
 
 blocks = sys.stdin.read().strip().split("\n\n")
 
 pairs = [tuple(json.loads(p) for p in block.split("\n")) for block in blocks]
 
+Packet: TypeAlias = list[int | list["Packet"]]
 
-def compare(lhs: list[int | list], rhs: list[int | list]) -> int:
 
+def compare(lhs: Packet, rhs: Packet) -> int:
     for lhs_a, rhs_a in zip(lhs, rhs):
         if isinstance(lhs_a, int) and isinstance(rhs_a, int):
             if lhs_a != rhs_a:
                 return rhs_a - lhs_a
         else:
             if not isinstance(lhs_a, list):
-                lhs_a = [lhs_a]
+                lhs_a = [lhs_a]  # type: ignore
             elif not isinstance(rhs_a, list):
-                rhs_a = [rhs_a]
+                rhs_a = [rhs_a]  # type: ignore
             assert isinstance(rhs_a, list) and isinstance(lhs_a, list)
-            r = compare(lhs_a, rhs_a)
+            r = compare(cast(Packet, lhs_a), cast(Packet, rhs_a))
             if r != 0:
                 return r
 

src/holt59/aoc/2022/day14.py

@@ -1,7 +1,4 @@
-# -*- encoding: utf-8 -*-
-
 import sys
-from collections import defaultdict
 from enum import Enum, auto
 from typing import Callable, cast
 
@@ -23,10 +20,10 @@ def print_blocks(blocks: dict[tuple[int, int], Cell]):
         blocks: Set of blocks to print.
     """
     x_min, y_min, x_max, y_max = (
-        min(x for x, y in blocks),
+        min(x for x, _ in blocks),
         0,
-        max(x for x, y in blocks),
-        max(y for x, y in blocks),
+        max(x for x, _ in blocks),
+        max(y for _, y in blocks),
     )
 
     for y in range(y_min, y_max + 1):
@@ -56,13 +53,12 @@ def flow(
         The input blocks.
     """
 
-    y_max = max(y for x, y in blocks)
+    y_max = max(y for _, y in blocks)
 
     while True:
         x, y = 500, 0
 
         while y <= y_max:
-
             moved = False
             for cx, cy in ((x, y + 1), (x - 1, y + 1), (x + 1, y + 1)):
                 if (cx, cy) not in blocks and fill_fn(cx, cy) == Cell.AIR:
@@ -117,10 +113,10 @@ print_blocks(blocks)
 print()
 
 x_min, y_min, x_max, y_max = (
-    min(x for x, y in blocks),
+    min(x for x, _ in blocks),
     0,
-    max(x for x, y in blocks),
-    max(y for x, y in blocks),
+    max(x for x, _ in blocks),
+    max(y for _, y in blocks),
 )
 
 # === part 1 ===

src/holt59/aoc/2022/day15.py

@@ -1,5 +1,3 @@
-# -*- encoding: utf-8 -*-
-
 import sys
 
 import numpy as np
@@ -7,7 +5,6 @@ import parse
 
 
 def part1(sensor_to_beacon: dict[tuple[int, int], tuple[int, int]], row: int) -> int:
-
     no_beacons_row_l: list[np.ndarray] = []
 
     for (sx, sy), (bx, by) in sensor_to_beacon.items():
@@ -37,7 +34,7 @@ def part2_intervals(
                 its.append((max(0, sx - dx), min(sx + dx, xy_max)))
 
         its = sorted(its)
-        s, e = its[0]
+        _, e = its[0]
 
         for si, ei in its[1:]:
             if si > e + 1:

src/holt59/aoc/2022/day16.py

@@ -1,5 +1,3 @@
-# -*- encoding: utf-8 -*-
-
 from __future__ import annotations
 
 import heapq
@@ -69,7 +67,6 @@ def part_1(
     distances: dict[tuple[Pipe, Pipe], int],
     relevant_pipes: FrozenSet[Pipe],
 ):
-
     node_at_times: dict[int, dict[Pipe, dict[FrozenSet[Pipe], int]]] = defaultdict(
         lambda: defaultdict(lambda: defaultdict(lambda: 0))
     )
@@ -79,7 +76,6 @@ def part_1(
         for c_pipe, nodes in node_at_times[time].items():
             for flowing, flow in nodes.items():
                 for target in relevant_pipes:
-
                     distance = distances[c_pipe, target] + 1
                     if time + distance >= max_time or target in flowing:
                         continue

src/holt59/aoc/2022/day17.py

@@ -1,5 +1,3 @@
-# -*- encoding: utf-8 -*-
-
 import sys
 from typing import Sequence, TypeVar
 
@@ -49,7 +47,6 @@ def build_tower(
     early_stop: bool = False,
     init: np.ndarray = np.ones(WIDTH, dtype=bool),
 ) -> tuple[np.ndarray, int, int, dict[int, int]]:
-
     tower = EMPTY_BLOCKS.copy()
     tower[0, :] = init
 
@@ -59,7 +56,6 @@ def build_tower(
     rock_count = 0
 
     for rock_count in range(n_rocks):
-
         if early_stop:
             if i_rock == 0 and (i_rock, i_jet) in done_at:
                 break
@@ -75,7 +71,6 @@ def build_tower(
             tower = np.concatenate([tower, EMPTY_BLOCKS], axis=0)
 
         while True:
-
             jet, i_jet = next_cycle(jets, i_jet)
 
             dx = 0

src/holt59/aoc/2022/day18.py

@@ -1,5 +1,3 @@
-# -*- encoding: utf-8 -*-
-
 import sys
 from typing import FrozenSet
 

src/holt59/aoc/2022/day19.py

@@ -1,5 +1,3 @@
-# -*- encoding: utf-8 -*-
-
 import sys
 from typing import Literal
 
@@ -88,7 +86,6 @@ for line in lines:
 
 
 def run(blueprint: dict[Reagent, dict[Reagent, int]], max_time: int) -> int:
-
     # since we can only build one robot per time, we do not need more than X robots
     # of type K where X is the maximum number of K required among all robots, e.g.,
     # in the first toy blueprint, we need at most 4 ore robots, 14 clay ones and 7
@@ -100,7 +97,6 @@ def run(blueprint: dict[Reagent, dict[Reagent, int]], max_time: int) -> int:
     state_after_t: dict[int, set[State]] = {0: [State()]}
 
     for t in range(1, max_time + 1):
-
         # list of new states at the end of step t that we are going to prune later
         states_for_t: set[State] = set()
 
@@ -178,7 +174,7 @@ def run(blueprint: dict[Reagent, dict[Reagent, int]], max_time: int) -> int:
 
 answer_1 = sum(
     (i_blueprint + 1) * run(blueprint, 24)
-    for i_blueprint, blueprint in enumerate(tqdm(blueprints))
+    for i_blueprint, blueprint in enumerate(blueprints)
 )
 print(f"answer 1 is {answer_1}")
 

src/holt59/aoc/2022/day2.py

@@ -1,20 +1,5 @@
-# -*- encoding: utf-8 -*-
-
 import sys
 
-lines = sys.stdin.readlines()
-
-# the solution relies on replacing rock / paper / scissor by values 0 / 1 / 2 and using
-# modulo-3 arithmetic
-#
-# in modulo-3 arithmetic, the winning move is 1 + the opponent move (e.g., winning move
-# if opponent plays 0 is 1, or 0 if opponent plays 2 (0 = (2 + 1 % 3)))
-#
-
-# we read the lines in a Nx2 in array with value 0/1/2 instead of A/B/C or X/Y/Z for
-# easier manipulation
-values = [(ord(row[0]) - ord("A"), ord(row[2]) - ord("X")) for row in lines]
-
 
 def score_1(ux: int, vx: int) -> int:
     # here ux and vx are both moves: 0 = rock, 1 = paper, 2 = scissor
@@ -48,8 +33,21 @@ def score_2(ux: int, vx: int) -> int:
     return (ux + vx - 1) % 3 + 1 + vx * 3
 
 
+lines = sys.stdin.readlines()
+
+# the solution relies on replacing rock / paper / scissor by values 0 / 1 / 2 and using
+# modulo-3 arithmetic
+#
+# in modulo-3 arithmetic, the winning move is 1 + the opponent move (e.g., winning move
+# if opponent plays 0 is 1, or 0 if opponent plays 2 (0 = (2 + 1 % 3)))
+#
+
+# we read the lines in a Nx2 in array with value 0/1/2 instead of A/B/C or X/Y/Z for
+# easier manipulation
+values = [(ord(row[0]) - ord("A"), ord(row[2]) - ord("X")) for row in lines]
+
 # part 1 - 13526
-print(f"score 1 is {sum(score_1(*v) for v in values)}")
+print(f"answer 1 is {sum(score_1(*v) for v in values)}")
 
 # part 2 - 14204
-print(f"score 2 is {sum(score_2(*v) for v in values)}")
+print(f"answer 2 is {sum(score_2(*v) for v in values)}")

src/holt59/aoc/2022/day20.py

@@ -0,0 +1,74 @@
+from __future__ import annotations
+
+import sys
+
+
+class Number:
+    current: int
+    value: int
+
+    def __init__(self, value: int):
+        self.current = 0
+        self.value = value
+
+    def __str__(self):
+        return str(self.value)
+
+    def __repr__(self):
+        return str(self)
+
+
+def decrypt(numbers: list[Number], key: int, rounds: int) -> int:
+    numbers = numbers.copy()
+    original = numbers.copy()
+
+    for index, number in enumerate(numbers):
+        number.current = index
+
+    for _ in range(rounds):
+        for number in original:
+            index = number.current
+            offset = (number.value * key) % (len(numbers) - 1)
+            target = index + offset
+
+            # need to wrap
+            if target >= len(numbers):
+                target = offset - (len(numbers) - index) + 1
+
+                for number_2 in numbers[target:index]:
+                    number_2.current += 1
+
+                numbers = (
+                    numbers[:target]
+                    + [number]
+                    + numbers[target:index]
+                    + numbers[index + 1 :]
+                )
+            else:
+                for number_2 in numbers[index : target + 1]:
+                    number_2.current -= 1
+
+                numbers = (
+                    numbers[:index]
+                    + numbers[index + 1 : target + 1]
+                    + [number]
+                    + numbers[target + 1 :]
+                )
+            number.current = target
+
+    index_of_0 = next(
+        filter(lambda index: numbers[index].value == 0, range(len(numbers)))
+    )
+    return sum(
+        numbers[(index_of_0 + offset) % len(numbers)].value * key
+        for offset in (1000, 2000, 3000)
+    )
+
+
+numbers = [Number(int(x)) for i, x in enumerate(sys.stdin.readlines())]
+
+answer_1 = decrypt(numbers, 1, 1)
+print(f"answer 1 is {answer_1}")
+
+answer_2 = decrypt(numbers, 811589153, 10)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2022/day21.py

@@ -0,0 +1,107 @@
+import operator
+import sys
+from typing import Callable
+
+
+def compute(monkeys: dict[str, int | tuple[str, str, str]], monkey: str) -> int:
+    value = monkeys[monkey]
+    if isinstance(value, int):
+        return value
+    else:
+        op: dict[str, Callable[[int, int], int]] = {
+            "+": operator.add,
+            "-": operator.sub,
+            "*": operator.mul,
+            "/": operator.floordiv,
+        }
+        value = op[value[1]](compute(monkeys, value[0]), compute(monkeys, value[2]))
+        monkeys[monkey] = value
+        return value
+
+
+def invert(
+    monkeys: dict[str, int | tuple[str, str, str]], monkey: str, target: int
+) -> dict[str, int | tuple[str, str, str]]:
+    """
+    Revert the given mapping from monkey name to value or operation such that
+    the value from 'monkey' is computable by inverting operation until the root is
+    found.
+
+    Args:
+        monkeys: Dictionary of monkeys, that will be updated and returned.
+        monkey: Name of the monkey to start from.
+        target: Target value to set for the monkey that depends on root.
+
+    Returns:
+        The given dictionary of monkeys.
+    """
+
+    monkeys = monkeys.copy()
+
+    depends: dict[str, str] = {}
+    for m, v in monkeys.items():
+        if isinstance(v, int):
+            continue
+
+        op1, _, op2 = v
+
+        assert op1 not in depends
+        assert op2 not in depends
+        depends[op1] = m
+        depends[op2] = m
+
+    invert_op = {"+": "-", "-": "+", "*": "/", "/": "*"}
+
+    current = monkey
+    while True:
+        dep = depends[current]
+
+        if dep == "root":
+            monkeys[current] = target
+            break
+
+        val = monkeys[dep]
+        assert not isinstance(val, int)
+
+        op1, ope, op2 = val
+
+        if op1 == current:
+            monkeys[current] = (dep, invert_op[ope], op2)
+        elif ope in ("+", "*"):
+            monkeys[current] = (dep, invert_op[ope], op1)
+        else:
+            monkeys[current] = (op1, ope, dep)
+
+        current = dep
+
+    return monkeys
+
+
+lines = sys.stdin.read().splitlines()
+
+monkeys: dict[str, int | tuple[str, str, str]] = {}
+
+op_monkeys: set[str] = set()
+
+for line in lines:
+    parts = line.split(":")
+    name = parts[0].strip()
+
+    try:
+        value = int(parts[1].strip())
+        monkeys[name] = value
+    except ValueError:
+        op1, ope, op2 = parts[1].strip().split()
+        monkeys[name] = (op1, ope, op2)
+
+        op_monkeys.add(name)
+
+
+answer_1 = compute(monkeys.copy(), "root")
+print(f"answer 1 is {answer_1}")
+
+# assume the second operand of 'root' can be computed, and the first one depends on
+# humn, which is the case is my input and the test input
+p1, _, p2 = monkeys["root"]  # type: ignore
+answer_2 = compute(invert(monkeys, "humn", compute(monkeys.copy(), p2)), "humn")
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2022/day22.py

@@ -0,0 +1,223 @@
+import re
+import sys
+from typing import Callable
+
+import numpy as np
+
+VOID, EMPTY, WALL = 0, 1, 2
+TILE_FROM_CHAR = {" ": VOID, ".": EMPTY, "#": WALL}
+
+SCORES = {"E": 0, "S": 1, "W": 2, "N": 3}
+
+
+board_map_s, direction_s = sys.stdin.read().split("\n\n")
+
+# board
+board_lines = board_map_s.splitlines()
+max_line = max(len(line) for line in board_lines)
+board = np.array(
+    [
+        [TILE_FROM_CHAR[c] for c in row] + [VOID] * (max_line - len(row))
+        for row in board_map_s.splitlines()
+    ]
+)
+
+directions = [
+    int(p1) if p2 else p1 for p1, p2 in re.findall(R"(([0-9])+|L|R)", direction_s)
+]
+
+
+# find on each row and column the first and last non-void
+row_first_non_void = np.argmax(board != VOID, axis=1)
+row_last_non_void = board.shape[1] - np.argmax(board[:, ::-1] != VOID, axis=1) - 1
+col_first_non_void = np.argmax(board != VOID, axis=0)
+col_last_non_void = board.shape[0] - np.argmax(board[::-1, :] != VOID, axis=0) - 1
+
+
+faces = np.zeros_like(board)
+size = np.gcd(board.shape[0], board.shape[1])
+for row in range(0, board.shape[0], size):
+    for col in range(row_first_non_void[row], row_last_non_void[row], size):
+        faces[row : row + size, col : col + size] = faces.max() + 1
+
+SIZE = np.gcd(*board.shape)
+
+# TODO: deduce this from the actual cube...
+faces_wrap: dict[int, dict[str, Callable[[int, int], tuple[int, int, str]]]]
+
+if board.shape == (12, 16):  # example
+    faces_wrap = {
+        1: {
+            "W": lambda y, x: (4, 4 + y, "S"),  # 3N
+            "N": lambda y, x: (4, 11 - x, "S"),  # 2N
+            "E": lambda y, x: (11 - y, 15, "W"),  # 6E
+        },
+        2: {
+            "W": lambda y, x: (11, 19 - y, "N"),  # 6S
+            "N": lambda y, x: (0, 11 - y, "S"),  # 1N
+            "S": lambda y, x: (11, 11 - x, "N"),  # 5S
+        },
+        3: {
+            "N": lambda y, x: (x - 4, 8, "E"),  # 1W
+            "S": lambda y, x: (15 - x, 8, "E"),  # 5W
+        },
+        4: {"E": lambda y, x: (8, 19 - y, "S")},  # 6N
+        5: {
+            "W": lambda y, x: (7, 15 - y, "N"),  # 3S
+            "S": lambda y, x: (7, 11 - x, "N"),  # 2S
+        },
+        6: {
+            "N": lambda y, x: (19 - x, 11, "W"),  # 4E
+            "E": lambda y, x: (11 - y, 11, "W"),  # 1E
+            "S": lambda y, x: (19 - x, 0, "E"),  # 2W
+        },
+    }
+
+else:
+    faces_wrap = {
+        1: {
+            "W": lambda y, x: (3 * SIZE - y - 1, 0, "E"),  # 4W
+            "N": lambda y, x: (2 * SIZE + x, 0, "E"),  # 6W
+        },
+        2: {
+            "N": lambda y, x: (4 * SIZE - 1, x - 2 * SIZE, "N"),  # 6S
+            "E": lambda y, x: (3 * SIZE - y - 1, 2 * SIZE - 1, "W"),  # 5E
+            "S": lambda y, x: (x - SIZE, 2 * SIZE - 1, "W"),  # 3E
+        },
+        3: {
+            "W": lambda y, x: (2 * SIZE, y - SIZE, "S"),  # 4N
+            "E": lambda y, x: (SIZE - 1, SIZE + y, "N"),  # 2S
+        },
+        4: {
+            "W": lambda y, x: (3 * SIZE - y - 1, SIZE, "E"),  # 1W
+            "N": lambda y, x: (SIZE + x, SIZE, "E"),  # 3W
+        },
+        5: {
+            "E": lambda y, x: (3 * SIZE - y - 1, 3 * SIZE - 1, "W"),  # 2E
+            "S": lambda y, x: (2 * SIZE + x, SIZE - 1, "W"),  # 6E
+        },
+        6: {
+            "W": lambda y, x: (0, y - 2 * SIZE, "S"),  # 1N
+            "E": lambda y, x: (3 * SIZE - 1, y - 2 * SIZE, "N"),  # 5S
+            "S": lambda y, x: (0, x + 2 * SIZE, "S"),  # 2N
+        },
+    }
+
+
+def wrap_part_1(y0: int, x0: int, r0: str) -> tuple[int, int, str]:
+    if r0 == "E":
+        return y0, row_first_non_void[y0], r0
+    elif r0 == "S":
+        return col_first_non_void[x0], x0, r0
+    elif r0 == "W":
+        return y0, row_last_non_void[y0], r0
+    elif r0 == "N":
+        return col_last_non_void[x0], x0, r0
+
+    assert False
+
+
+def wrap_part_2(y0: int, x0: int, r0: str) -> tuple[int, int, str]:
+    cube = faces[y0, x0]
+    assert r0 in faces_wrap[cube]
+    return faces_wrap[cube][r0](y0, x0)
+
+
+def run(wrap: Callable[[int, int, str], tuple[int, int, str]]) -> tuple[int, int, str]:
+    y0 = 0
+    x0 = np.where(board[0] == EMPTY)[0][0]
+    r0 = "E"
+
+    for direction in directions:
+        if isinstance(direction, int):
+            while direction > 0:
+                if r0 == "E":
+                    xi = np.where(board[y0, x0 + 1 : x0 + direction + 1] == WALL)[0]
+                    if len(xi):
+                        x0 = x0 + xi[0]
+                        direction = 0
+                    elif (
+                        x0 + direction < board.shape[1]
+                        and board[y0, x0 + direction] == EMPTY
+                    ):
+                        x0 = x0 + direction
+                        direction = 0
+                    else:
+                        y0_t, x0_t, r0_t = wrap(y0, x0, r0)
+                        if board[y0_t, x0_t] == WALL:
+                            x0 = row_last_non_void[y0]
+                            direction = 0
+                        else:
+                            direction = direction - (row_last_non_void[y0] - x0) - 1
+                            y0, x0, r0 = y0_t, x0_t, r0_t
+                elif r0 == "S":
+                    yi = np.where(board[y0 + 1 : y0 + direction + 1, x0] == WALL)[0]
+                    if len(yi):
+                        y0 = y0 + yi[0]
+                        direction = 0
+                    elif (
+                        y0 + direction < board.shape[0]
+                        and board[y0 + direction, x0] == EMPTY
+                    ):
+                        y0 = y0 + direction
+                        direction = 0
+                    else:
+                        y0_t, x0_t, r0_t = wrap(y0, x0, r0)
+                        if board[y0_t, x0_t] == WALL:
+                            y0 = col_last_non_void[x0]
+                            direction = 0
+                        else:
+                            direction = direction - (col_last_non_void[x0] - y0) - 1
+                            y0, x0, r0 = y0_t, x0_t, r0_t
+                elif r0 == "W":
+                    left = max(x0 - direction - 1, 0)
+                    xi = np.where(board[y0, left:x0] == WALL)[0]
+                    if len(xi):
+                        x0 = left + xi[-1] + 1
+                        direction = 0
+                    elif x0 - direction >= 0 and board[y0, x0 - direction] == EMPTY:
+                        x0 = x0 - direction
+                        direction = 0
+                    else:
+                        y0_t, x0_t, r0_t = wrap(y0, x0, r0)
+                        if board[y0_t, x0_t] == WALL:
+                            x0 = row_first_non_void[y0]
+                            direction = 0
+                        else:
+                            direction = direction - (x0 - row_first_non_void[y0]) - 1
+                            y0, x0, r0 = y0_t, x0_t, r0_t
+                elif r0 == "N":
+                    top = max(y0 - direction - 1, 0)
+                    yi = np.where(board[top:y0, x0] == WALL)[0]
+                    if len(yi):
+                        y0 = top + yi[-1] + 1
+                        direction = 0
+                    elif y0 - direction >= 0 and board[y0 - direction, x0] == EMPTY:
+                        y0 = y0 - direction
+                        direction = 0
+                    else:
+                        y0_t, x0_t, r0_t = wrap(y0, x0, r0)
+                        if board[y0_t, x0_t] == WALL:
+                            y0 = col_first_non_void[x0]
+                            direction = 0
+                        else:
+                            direction = direction - (y0 - col_first_non_void[x0]) - 1
+                            y0, x0, r0 = y0_t, x0_t, r0_t
+        else:
+            r0 = {
+                "E": {"L": "N", "R": "S"},
+                "N": {"L": "W", "R": "E"},
+                "W": {"L": "S", "R": "N"},
+                "S": {"L": "E", "R": "W"},
+            }[r0][direction]
+
+    return y0, x0, r0
+
+
+y1, x1, r1 = run(wrap_part_1)
+answer_1 = 1000 * (1 + y1) + 4 * (1 + x1) + SCORES[r1]
+print(f"answer 1 is {answer_1}")
+
+y2, x2, r2 = run(wrap_part_2)
+answer_2 = 1000 * (1 + y2) + 4 * (1 + x2) + SCORES[r2]
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2022/day23.py

@@ -0,0 +1,103 @@
+import itertools
+import sys
+from collections import defaultdict
+
+Directions = list[
+    tuple[
+        str, tuple[int, int], tuple[tuple[int, int], tuple[int, int], tuple[int, int]]
+    ]
+]
+
+# (Y, X)
+DIRECTIONS: Directions = [
+    ("N", (-1, 0), ((-1, -1), (-1, 0), (-1, 1))),
+    ("S", (1, 0), ((1, -1), (1, 0), (1, 1))),
+    ("W", (0, -1), ((-1, -1), (0, -1), (1, -1))),
+    ("E", (0, 1), ((-1, 1), (0, 1), (1, 1))),
+]
+
+
+def min_max_yx(positions: set[tuple[int, int]]) -> tuple[int, int, int, int]:
+    ys, xs = {y for y, x in positions}, {x for y, x in positions}
+    return min(ys), min(xs), max(ys), max(xs)
+
+
+def print_positions(positions: set[tuple[int, int]]):
+    min_y, min_x, max_y, max_x = min_max_yx(positions)
+    print(
+        "\n".join(
+            "".join(
+                "#" if (y, x) in positions else "." for x in range(min_x - 1, max_x + 2)
+            )
+            for y in range(min_y - 1, max_y + 2)
+        )
+    )
+
+
+def round(
+    positions: set[tuple[int, int]],
+    directions: Directions,
+):
+    to_move: dict[tuple[int, int], list[tuple[int, int]]] = defaultdict(lambda: [])
+    for y, x in positions:
+        elves = {
+            (dy, dx): (y + dy, x + dx) in positions
+            for dy, dx in itertools.product((-1, 0, 1), (-1, 0, 1))
+            if (dy, dx) != (0, 0)
+        }
+
+        if not any(elves.values()):
+            to_move[y, x].append((y, x))
+            continue
+
+        found: str | None = None
+        for d, (dy, dx), d_yx_check in directions:
+            if not any(elves[dy, dx] for dy, dx in d_yx_check):
+                found = d
+                to_move[y + dy, x + dx].append((y, x))
+                break
+        if found is None:
+            to_move[y, x].append((y, x))
+
+    positions.clear()
+    for ty, tx in to_move:
+        if len(to_move[ty, tx]) > 1:
+            positions.update(to_move[ty, tx])
+        else:
+            positions.add((ty, tx))
+
+    directions.append(directions.pop(0))
+
+
+POSITIONS = {
+    (i, j)
+    for i, row in enumerate(sys.stdin.read().splitlines())
+    for j, col in enumerate(row)
+    if col == "#"
+}
+
+# === part 1 ===
+
+p1, d1 = POSITIONS.copy(), DIRECTIONS.copy()
+for r in range(10):
+    round(p1, d1)
+
+min_y, min_x, max_y, max_x = min_max_yx(p1)
+answer_1 = sum(
+    (y, x) not in p1 for y in range(min_y, max_y + 1) for x in range(min_x, max_x + 1)
+)
+print(f"answer 1 is {answer_1}")
+
+# === part 2 ===
+
+p2, d2 = POSITIONS.copy(), DIRECTIONS.copy()
+answer_2 = 0
+while True:
+    answer_2 += 1
+    backup = p2.copy()
+    round(p2, d2)
+
+    if backup == p2:
+        break
+
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2022/day24.py

@@ -0,0 +1,98 @@
+import heapq
+import math
+import sys
+from collections import defaultdict
+
+lines = sys.stdin.read().splitlines()
+
+winds = {
+    (i - 1, j - 1, lines[i][j])
+    for i in range(1, len(lines) - 1)
+    for j in range(1, len(lines[i]) - 1)
+    if lines[i][j] != "."
+}
+
+n_rows, n_cols = len(lines) - 2, len(lines[0]) - 2
+CYCLE = math.lcm(n_rows, n_cols)
+
+east_winds = [{j for j in range(n_cols) if (i, j, ">") in winds} for i in range(n_rows)]
+west_winds = [{j for j in range(n_cols) if (i, j, "<") in winds} for i in range(n_rows)]
+north_winds = [
+    {i for i in range(n_rows) if (i, j, "^") in winds} for j in range(n_cols)
+]
+south_winds = [
+    {i for i in range(n_rows) if (i, j, "v") in winds} for j in range(n_cols)
+]
+
+
+def run(start: tuple[int, int], start_cycle: int, end: tuple[int, int]):
+    def heuristic(y: int, x: int) -> int:
+        return abs(end[0] - y) + abs(end[1] - x)
+
+    # (distance + heuristic, distance, (start_pos, cycle))
+    queue = [(heuristic(start[0], start[1]), 0, ((start[0], start[1]), start_cycle))]
+    visited: set[tuple[tuple[int, int], int]] = set()
+    distances: dict[tuple[int, int], dict[int, int]] = defaultdict(lambda: {})
+
+    while queue:
+        _, distance, ((y, x), cycle) = heapq.heappop(queue)
+
+        if ((y, x), cycle) in visited:
+            continue
+
+        distances[y, x][cycle] = distance
+
+        visited.add(((y, x), cycle))
+
+        if (y, x) == (end[0], end[1]):
+            break
+
+        for dy, dx in (0, 0), (-1, 0), (1, 0), (0, -1), (0, 1):
+            ty = y + dy
+            tx = x + dx
+
+            n_cycle = (cycle + 1) % CYCLE
+
+            if (ty, tx) == end:
+                heapq.heappush(queue, (distance + 1, distance + 1, ((ty, tx), n_cycle)))
+                break
+
+            if ((ty, tx), n_cycle) in visited:
+                continue
+
+            if (ty, tx) != start and (ty < 0 or tx < 0 or ty >= n_rows or tx >= n_cols):
+                continue
+
+            if (ty, tx) != start:
+                if (ty - n_cycle) % n_rows in south_winds[tx]:
+                    continue
+                if (ty + n_cycle) % n_rows in north_winds[tx]:
+                    continue
+                if (tx + n_cycle) % n_cols in west_winds[ty]:
+                    continue
+                if (tx - n_cycle) % n_cols in east_winds[ty]:
+                    continue
+
+            heapq.heappush(
+                queue,
+                ((heuristic(ty, tx) + distance + 1, distance + 1, ((ty, tx), n_cycle))),
+            )
+
+    return distances, next(iter(distances[end].values()))
+
+
+start = (
+    -1,
+    next(j for j in range(1, len(lines[0]) - 1) if lines[0][j] == ".") - 1,
+)
+end = (
+    n_rows,
+    next(j for j in range(1, len(lines[-1]) - 1) if lines[-1][j] == ".") - 1,
+)
+
+distances_1, forward_1 = run(start, 0, end)
+print(f"answer 1 is {forward_1}")
+
+distances_2, return_1 = run(end, next(iter(distances_1[end].keys())), start)
+distances_3, forward_2 = run(start, next(iter(distances_2[start].keys())), end)
+print(f"answer 2 is {forward_1 + return_1 + forward_2}")

src/holt59/aoc/2022/day25.py

@@ -0,0 +1,27 @@
+import sys
+
+lines = sys.stdin.read().splitlines()
+
+coeffs = {"2": 2, "1": 1, "0": 0, "-": -1, "=": -2}
+
+
+def snafu2number(number: str) -> int:
+    value = 0
+    for c in number:
+        value *= 5
+        value += coeffs[c]
+    return value
+
+
+def number2snafu(number: int) -> str:
+    values = ["0", "1", "2", "=", "-"]
+    res = ""
+    while number > 0:
+        mod = number % 5
+        res = res + values[mod]
+        number = number // 5 + int(mod >= 3)
+    return "".join(reversed(res))
+
+
+answer_1 = number2snafu(sum(map(snafu2number, lines)))
+print(f"answer 1 is {answer_1}")

src/holt59/aoc/2022/day3.py

@@ -1,5 +1,3 @@
-# -*- encoding: utf-8 -*-
-
 import string
 import sys
 
@@ -13,13 +11,13 @@ priorities = {c: i + 1 for i, c in enumerate(string.ascii_letters)}
 
 # part 1
 part1 = sum(priorities[c] for p1, p2 in parts for c in p1.intersection(p2))
-print(f"score 1 is {part1}")
+print(f"answer 1 is {part1}")
 
 # part 2
 n_per_group = 3
 part2 = sum(
     priorities[c]
     for i in range(0, len(lines), n_per_group)
-    for c in set.intersection(*map(set, (lines[i : i + n_per_group])))
+    for c in set(lines[i]).intersection(*lines[i + 1 : i + n_per_group])
 )
-print(f"score 2 is {part2}")
+print(f"answer 2 is {part2}")

src/holt59/aoc/2022/day4.py

@@ -1,5 +1,3 @@
-# -*- encoding: utf-8 -*-
-
 import sys
 
 lines = [line.strip() for line in sys.stdin.readlines()]
@@ -12,8 +10,8 @@ def make_range(value: str) -> set[int]:
 
 sections = [tuple(make_range(part) for part in line.split(",")) for line in lines]
 
-score_1 = sum(s1.issubset(s2) or s2.issubset(s1) for s1, s2 in sections)
-print(f"score 1 is {score_1}")
+answer_1 = sum(s1.issubset(s2) or s2.issubset(s1) for s1, s2 in sections)
+print(f"answer 1 is {answer_1}")
 
-score_2 = sum(bool(s1.intersection(s2)) for s1, s2 in sections)
-print(f"score 1 is {score_2}")
+answer_2 = sum(bool(s1.intersection(s2)) for s1, s2 in sections)
+print(f"answer 1 is {answer_2}")

src/holt59/aoc/2022/day5.py

@@ -1,5 +1,3 @@
-# -*- encoding: utf-8 -*-
-
 import copy
 import sys
 

src/holt59/aoc/2022/day6.py

@@ -1,9 +1,5 @@
-# -*- encoding: utf-8 -*-
-
 import sys
 
-data = sys.stdin.read().strip()
-
 
 def index_of_first_n_differents(data: str, n: int) -> int:
     for i in range(len(data)):
@@ -12,5 +8,8 @@ def index_of_first_n_differents(data: str, n: int) -> int:
     return -1
 
 
+data = sys.stdin.read().strip()
+
+
 print(f"answer 1 is {index_of_first_n_differents(data, 4)}")
 print(f"answer 2 is {index_of_first_n_differents(data, 14)}")

src/holt59/aoc/2022/day7.py

@@ -1,5 +1,3 @@
-# -*- encoding: utf-8 -*-
-
 import sys
 from pathlib import Path
 

src/holt59/aoc/2022/day8.py

@@ -1,8 +1,7 @@
-# -*- encoding: utf-8 -*-
-
 import sys
 
 import numpy as np
+from numpy.typing import NDArray
 
 lines = sys.stdin.read().splitlines()
 
@@ -27,7 +26,7 @@ answer_1 = (highest_trees.min(axis=2) < trees).sum()
 print(f"answer 1 is {answer_1}")
 
 
-def viewing_distance(row_of_trees: np.ndarray, value: int) -> int:
+def viewing_distance(row_of_trees: NDArray[np.int_], value: int) -> int:
     w = np.where(row_of_trees >= value)[0]
 
     if not w.size:

src/holt59/aoc/2022/day9.py

@@ -1,12 +1,9 @@
-# -*- encoding: utf-8 -*-
-
 import sys
 
 import numpy as np
 
 
 def move(head: tuple[int, int], command: str) -> tuple[int, int]:
-
     h_col, h_row = head
 
     if command == "L":
@@ -22,7 +19,6 @@ def move(head: tuple[int, int], command: str) -> tuple[int, int]:
 
 
 def follow(head: tuple[int, int], tail: tuple[int, int]) -> tuple[int, int]:
-
     h_col, h_row = head
     t_col, t_row = tail
 
@@ -33,8 +29,7 @@ def follow(head: tuple[int, int], tail: tuple[int, int]) -> tuple[int, int]:
 
 
 def run(commands: list[str], n_blocks: int) -> list[tuple[int, int]]:
-
-    blocks = [(0, 0) for _ in range(n_blocks)]
+    blocks: list[tuple[int, int]] = [(0, 0) for _ in range(n_blocks)]
     visited = [blocks[-1]]
 
     for command in commands:

src/holt59/aoc/2023/day1.py

@@ -0,0 +1,45 @@
+import sys
+
+lines = sys.stdin.read().splitlines()
+
+lookups_1 = {str(d): d for d in range(1, 10)}
+lookups_2 = lookups_1 | {
+    d: i + 1
+    for i, d in enumerate(
+        (
+            "one",
+            "two",
+            "three",
+            "four",
+            "five",
+            "six",
+            "seven",
+            "eight",
+            "nine",
+        )
+    )
+}
+
+
+def find_values(lookups: dict[str, int]) -> list[int]:
+    values: list[int] = []
+
+    for line in filter(bool, lines):
+        first_digit = min(
+            lookups,
+            key=lambda lookup: index
+            if (index := line.find(lookup)) >= 0
+            else len(line),
+        )
+        last_digit = max(
+            lookups,
+            key=lambda lookup: index if (index := line.rfind(lookup)) >= 0 else -1,
+        )
+
+        values.append(10 * lookups[first_digit] + lookups[last_digit])
+
+    return values
+
+
+print(f"answer 1 is {sum(find_values(lookups_1))}")
+print(f"answer 2 is {sum(find_values(lookups_2))}")

src/holt59/aoc/2023/day10.py

@@ -0,0 +1,100 @@
+import os
+import sys
+from typing import Literal, cast
+
+VERBOSE = os.getenv("AOC_VERBOSE") == "True"
+
+Symbol = Literal["|", "-", "L", "J", "7", "F", ".", "S"]
+
+lines: list[list[Symbol]] = [
+    [cast(Symbol, symbol) for symbol in line] for line in sys.stdin.read().splitlines()
+]
+
+# find starting point
+si, sj = next(
+    (i, j)
+    for i in range(len(lines))
+    for j in range(len(lines[0]))
+    if lines[i][j] == "S"
+)
+
+# find one of the two outputs
+ni, nj = si, sj
+for ni, nj, chars in (
+    (si - 1, sj, "|7F"),
+    (si + 1, sj, "|LJ"),
+    (si, sj - 1, "-LF"),
+    (si, sj + 1, "-J7"),
+):
+    if lines[ni][nj] in chars:
+        break
+
+# part 1 - find the loop (re-used in part 2)
+loop = [(si, sj), (ni, nj)]
+while True:
+    pi, pj = loop[-2]
+    i, j = loop[-1]
+
+    sym = lines[i][j]
+
+    if sym == "|" and pi > i or sym in "JL" and pi == i:
+        i -= 1
+    elif sym == "|" and pi < i or sym in "7F" and pi == i:
+        i += 1
+    elif sym == "-" and pj > j or sym in "J7" and pj == j:
+        j -= 1
+    elif sym == "-" and pj < j or sym in "LF" and pj == j:
+        j += 1
+
+    if (i, j) == (si, sj):
+        break
+
+    loop.append((i, j))
+
+answer_1 = len(loop) // 2
+print(f"answer 1 is {answer_1}")
+
+# part 2
+
+# replace S by an appropriate character for the loop below
+di1, dj1 = loop[1][0] - loop[0][0], loop[1][1] - loop[0][1]
+di2, dj2 = loop[0][0] - loop[-1][0], loop[0][1] - loop[-1][1]
+mapping: dict[tuple[int, int], dict[tuple[int, int], Symbol]] = {
+    (0, 1): {(0, 1): "-", (-1, 0): "F", (1, 0): "L"},
+    (0, -1): {(0, -1): "-", (-1, 0): "7", (1, 0): "J"},
+    (1, 0): {(1, 0): "|", (0, 1): "7", (0, -1): "F"},
+    (-1, 0): {(-1, 0): "|", (0, -1): "L", (0, 1): "J"},
+}
+lines[si][sj] = mapping[di1, dj1][di2, dj2]
+
+# find the points inside the loop using an adaptation of ray casting for a discrete
+# grid (https://stackoverflow.com/a/218081/2666289)
+#
+# use a set for faster '... in loop' check
+#
+loop_s = set(loop)
+inside: set[tuple[int, int]] = set()
+for i in range(len(lines)):
+    cnt = 0
+    for j in range(len(lines[0])):
+        if (i, j) not in loop_s and cnt % 2 == 1:
+            inside.add((i, j))
+
+        if (i, j) in loop_s and lines[i][j] in "|LJ":
+            cnt += 1
+
+if VERBOSE:
+    for i in range(len(lines)):
+        for j in range(len(lines[0])):
+            if (i, j) == (si, sj):
+                print("\033[91mS\033[0m", end="")
+            elif (i, j) in loop:
+                print(lines[i][j], end="")
+            elif (i, j) in inside:
+                print("\033[92mI\033[0m", end="")
+            else:
+                print(".", end="")
+        print()
+
+answer_2 = len(inside)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2023/day11.py

@@ -0,0 +1,41 @@
+import sys
+
+import numpy as np
+
+lines = sys.stdin.read().splitlines()
+
+data = np.array([[c == "#" for c in line] for line in lines])
+
+rows = {c for c in range(data.shape[0]) if not data[c, :].any()}
+columns = {c for c in range(data.shape[1]) if not data[:, c].any()}
+
+galaxies_y, galaxies_x = np.where(data)  # type: ignore
+
+
+def compute_total_distance(expansion: int) -> int:
+    distances: list[int] = []
+    for g1 in range(len(galaxies_y)):
+        x1, y1 = int(galaxies_x[g1]), int(galaxies_y[g1])
+        for g2 in range(g1 + 1, len(galaxies_y)):
+            x2, y2 = int(galaxies_x[g2]), int(galaxies_y[g2])
+
+            dx = sum(
+                1 + (expansion - 1) * (x in columns)
+                for x in range(min(x1, x2), max(x1, x2))
+            )
+            dy = sum(
+                1 + (expansion - 1) * (y in rows)
+                for y in range(min(y1, y2), max(y1, y2))
+            )
+
+            distances.append(dx + dy)
+    return sum(distances)
+
+
+# part 1
+answer_1 = compute_total_distance(2)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = compute_total_distance(1000000)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2023/day12.py

@@ -0,0 +1,107 @@
+import os
+import sys
+from functools import lru_cache
+from typing import Iterable
+
+VERBOSE = os.getenv("AOC_VERBOSE") == "True"
+
+
+@lru_cache
+def compute_fitting_arrangements(pattern: str, counts: tuple[int, ...]) -> int:
+    """
+    fn3p tries to fit ALL values in counts() inside the pattern.
+    """
+    # no pattern -> ok if nothing to fit, otherwise ko
+    if not pattern:
+        count = 1 if not counts else 0
+
+    # no count -> ok if pattern has no mandatory entry, else ko
+    elif not counts:
+        count = 1 if pattern.find("#") == -1 else 0
+
+    # cannot fit all values -> ko
+    elif len(pattern) < sum(counts) + len(counts) - 1:
+        count = 0
+
+    elif len(pattern) < counts[0]:
+        count = 0
+
+    else:
+        count = 0
+
+        if pattern[0] == "?":
+            count += compute_fitting_arrangements(pattern[1:], counts)
+
+        if len(pattern) == counts[0]:
+            count += 1
+
+        elif pattern[counts[0]] != "#":
+            count += compute_fitting_arrangements(pattern[counts[0] + 1 :], counts[1:])
+
+    return count
+
+
+@lru_cache
+def compute_possible_arrangements(
+    patterns: tuple[str, ...], counts: tuple[int, ...]
+) -> int:
+    if not patterns:
+        return 1 if not counts else 0
+
+    with_hash = sum(1 for p in patterns[1:] if p.find("#") >= 0)
+
+    if with_hash > len(counts):
+        return 0
+
+    to_fit = counts if with_hash == 0 else counts[:-with_hash]
+    remaining = () if with_hash == 0 else counts[-with_hash:]
+
+    if not to_fit:
+        if patterns[0].find("#") != -1:
+            return 0
+        return compute_possible_arrangements(patterns[1:], remaining)
+
+    elif patterns[0].find("#") != -1 and len(patterns[0]) < to_fit[0]:
+        return 0
+
+    elif patterns[0].find("?") == -1:
+        if len(patterns[0]) != to_fit[0]:
+            return 0
+        return compute_possible_arrangements(patterns[1:], counts[1:])
+
+    else:
+        return sum(
+            fp * compute_possible_arrangements(patterns[1:], to_fit[i:] + remaining)
+            for i in range(len(to_fit) + 1)
+            if (fp := compute_fitting_arrangements(patterns[0], to_fit[:i])) > 0
+        )
+
+
+def compute_all_possible_arrangements(lines: Iterable[str], repeat: int) -> int:
+    count = 0
+
+    if VERBOSE:
+        from tqdm import tqdm
+
+        lines = tqdm(lines)
+
+    for line in lines:
+        parts = line.split(" ")
+        count += compute_possible_arrangements(
+            tuple(filter(len, "?".join(parts[0] for _ in range(repeat)).split("."))),
+            tuple(int(c) for c in parts[1].split(",")) * repeat,
+        )
+
+    return count
+
+
+lines = sys.stdin.read().splitlines()
+
+
+# part 1
+answer_1 = compute_all_possible_arrangements(lines, 1)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = compute_all_possible_arrangements(lines, 5)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2023/day13.py

@@ -0,0 +1,43 @@
+import sys
+from typing import Callable, Literal
+
+
+def split(block: list[str], axis: Literal[0, 1], count: int) -> int:
+    n_iter = len(block) if axis == 0 else len(block[0])
+    n_check = len(block) if axis == 1 else len(block[0])
+
+    at: Callable[[int, int], str] = (
+        (lambda i, j: block[i][j]) if axis == 0 else (lambda i, j: block[j][i])
+    )
+
+    for i in range(n_iter - 1):
+        size = min(i + 1, n_iter - i - 1)
+        if (
+            sum(
+                at(i - s, j) != at(i + 1 + s, j)
+                for s in range(0, size)
+                for j in range(n_check)
+            )
+            == count
+        ):
+            return i + 1
+
+    return 0
+
+
+blocks = [block.splitlines() for block in sys.stdin.read().split("\n\n")]
+
+
+# part 1
+answer_1 = sum(
+    split(block, axis=1, count=0) + 100 * split(block, axis=0, count=0)
+    for block in blocks
+)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = sum(
+    split(block, axis=1, count=1) + 100 * split(block, axis=0, count=1)
+    for block in blocks
+)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2023/day14.py

@@ -0,0 +1,68 @@
+import sys
+from typing import TypeAlias
+
+RockGrid: TypeAlias = list[list[str]]
+
+rocks0 = [list(line) for line in sys.stdin.read().splitlines()]
+
+
+def slide_rocks_top(rocks: RockGrid) -> RockGrid:
+    top = [0 if c == "." else 1 for c in rocks[0]]
+    for row in range(1, len(rocks)):
+        for col in range(len(rocks[0])):
+            match rocks[row][col]:
+                case "O":
+                    if top[col] != row:
+                        rocks[top[col]][col] = "O"
+                        rocks[row][col] = "."
+                    top[col] = top[col] + 1
+                case "#":
+                    top[col] = row + 1
+                case _:
+                    pass
+    return rocks
+
+
+def cycle(rocks: RockGrid) -> RockGrid:
+    for _ in range(4):
+        rocks = slide_rocks_top(rocks)
+        rocks = [
+            [rocks[len(rocks) - j - 1][i] for j in range(len(rocks))]
+            for i in range(len(rocks[0]))
+        ]
+
+    return rocks
+
+
+rocks = slide_rocks_top([[c for c in r] for r in rocks0])
+
+# part 1
+answer_1 = sum(
+    (len(rocks) - i) * sum(1 for c in row if c == "O") for i, row in enumerate(rocks)
+)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+rocks = rocks0
+
+N = 1000000000
+cycles: list[RockGrid] = []
+i_cycle: int = -1
+for i_cycle in range(N):
+    rocks = cycle(rocks)
+
+    if any(rocks == c for c in cycles):
+        break
+
+    cycles.append([[c for c in r] for r in rocks])
+
+cycle_start = next(i for i in range(len(cycles)) if (rocks == cycles[i]))
+cycle_length = i_cycle - cycle_start
+
+ci = cycle_start + (N - cycle_start) % cycle_length - 1
+
+answer_2 = sum(
+    (len(rocks) - i) * sum(1 for c in row if c == "O")
+    for i, row in enumerate(cycles[ci])
+)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2023/day15.py

@@ -0,0 +1,31 @@
+import sys
+from functools import reduce
+
+steps = sys.stdin.read().strip().split(",")
+
+
+def _hash(s: str) -> int:
+    return reduce(lambda v, u: ((v + ord(u)) * 17) % 256, s, 0)
+
+
+# part 1
+answer_1 = sum(map(_hash, steps))
+print(f"answer 1 is {answer_1}")
+
+# part 2
+boxes: list[dict[str, int]] = [{} for _ in range(256)]
+
+for step in steps:
+    if (i := step.find("=")) >= 0:
+        label, length = step[:i], int(step[i + 1 :])
+        boxes[_hash(label)][label] = length
+    else:
+        label = step[:-1]
+        boxes[_hash(label)].pop(label, None)
+
+answer_2 = sum(
+    i_box * i_lens * length
+    for i_box, box in enumerate(boxes, start=1)
+    for i_lens, length in enumerate(box.values(), start=1)
+)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2023/day16.py

@@ -0,0 +1,110 @@
+import os
+import sys
+from typing import Literal, TypeAlias, cast
+
+VERBOSE = os.getenv("AOC_VERBOSE") == "True"
+
+CellType: TypeAlias = Literal[".", "|", "-", "\\", "/"]
+Direction: TypeAlias = Literal["R", "L", "U", "D"]
+
+Mappings: dict[
+    CellType,
+    dict[
+        Direction,
+        tuple[tuple[tuple[int, int, Direction], ...], tuple[Direction, ...]],
+    ],
+] = {
+    ".": {
+        "R": (((0, +1, "R"),), ("R", "L")),
+        "L": (((0, -1, "L"),), ("R", "L")),
+        "U": (((-1, 0, "U"),), ("U", "D")),
+        "D": (((+1, 0, "D"),), ("U", "D")),
+    },
+    "-": {
+        "R": (((0, +1, "R"),), ("R", "L")),
+        "L": (((0, -1, "L"),), ("R", "L")),
+        "U": (((0, +1, "R"), (0, -1, "L")), ("U", "D")),
+        "D": (((0, +1, "R"), (0, -1, "L")), ("U", "D")),
+    },
+    "|": {
+        "U": (((-1, 0, "U"),), ("U", "D")),
+        "D": (((+1, 0, "D"),), ("U", "D")),
+        "R": (((-1, 0, "U"), (+1, 0, "D")), ("R", "L")),
+        "L": (((-1, 0, "U"), (+1, 0, "D")), ("R", "L")),
+    },
+    "/": {
+        "R": (((-1, 0, "U"),), ("R", "D")),
+        "L": (((+1, 0, "D"),), ("L", "U")),
+        "U": (((0, +1, "R"),), ("U", "L")),
+        "D": (((0, -1, "L"),), ("R", "D")),
+    },
+    "\\": {
+        "R": (((+1, 0, "D"),), ("R", "U")),
+        "L": (((-1, 0, "U"),), ("L", "D")),
+        "U": (((0, -1, "L"),), ("U", "R")),
+        "D": (((0, +1, "R"),), ("L", "D")),
+    },
+}
+
+
+def propagate(
+    layout: list[list[CellType]], start: tuple[int, int], direction: Direction
+) -> list[list[tuple[Direction, ...]]]:
+    n_rows, n_cols = len(layout), len(layout[0])
+
+    beams: list[list[tuple[Direction, ...]]] = [
+        [() for _ in range(len(layout[0]))] for _ in range(len(layout))
+    ]
+
+    queue = [(start, direction)]
+
+    while queue:
+        (row, col), direction = queue.pop()
+
+        if (
+            row not in range(0, n_rows)
+            or col not in range(0, n_cols)
+            or direction in beams[row][col]
+        ):
+            continue
+
+        moves, update = Mappings[layout[row][col]][direction]
+
+        beams[row][col] += update
+
+        for move in moves:
+            queue.append(((row + move[0], col + move[1]), move[2]))
+
+    return beams
+
+
+layout: list[list[CellType]] = [
+    [cast(CellType, col) for col in row] for row in sys.stdin.read().splitlines()
+]
+
+
+beams = propagate(layout, (0, 0), "R")
+
+if VERBOSE:
+    print("\n".join(["".join("#" if col else "." for col in row) for row in beams]))
+
+# part 1
+answer_1 = sum(sum(map(bool, row)) for row in beams)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+n_rows, n_cols = len(layout), len(layout[0])
+cases: list[tuple[tuple[int, int], Direction]] = []
+
+for row in range(n_rows):
+    cases.append(((row, 0), "R"))
+    cases.append(((row, n_cols - 1), "L"))
+for col in range(n_cols):
+    cases.append(((0, col), "D"))
+    cases.append(((n_rows - 1, col), "U"))
+
+answer_2 = max(
+    sum(sum(map(bool, row)) for row in propagate(layout, start, direction))
+    for start, direction in cases
+)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2023/day17.py

@@ -0,0 +1,233 @@
+from __future__ import annotations
+
+import heapq
+import os
+import sys
+from collections import defaultdict
+from dataclasses import dataclass
+from typing import Literal, TypeAlias
+
+VERBOSE = os.getenv("AOC_VERBOSE") == "True"
+
+Direction: TypeAlias = Literal[">", "<", "^", "v"]
+
+
+@dataclass(frozen=True, order=True)
+class Label:
+    row: int
+    col: int
+
+    direction: Direction
+    count: int
+
+    parent: Label | None = None
+
+
+# mappings from direction to row shift / col shift / opposite direction
+MAPPINGS: dict[Direction, tuple[int, int, Direction]] = {
+    ">": (0, +1, "<"),
+    "<": (0, -1, ">"),
+    "v": (+1, 0, "^"),
+    "^": (-1, 0, "v"),
+}
+
+
+def print_shortest_path(
+    grid: list[list[int]],
+    target: tuple[int, int],
+    per_cell: dict[tuple[int, int], list[tuple[Label, int]]],
+):
+    assert len(per_cell[target]) == 1
+    label = per_cell[target][0][0]
+
+    path: list[Label] = []
+    while True:
+        path.insert(0, label)
+        if label.parent is None:
+            break
+        label = label.parent
+
+    p_grid = [[str(c) for c in r] for r in grid]
+
+    for i in range(len(grid)):
+        for j in range(len(grid[0])):
+            if per_cell[i, j]:
+                p_grid[i][j] = f"\033[94m{grid[i][j]}\033[0m"
+
+    prev_label = path[0]
+    for label in path[1:]:
+        for r in range(
+            min(prev_label.row, label.row), max(prev_label.row, label.row) + 1
+        ):
+            for c in range(
+                min(prev_label.col, label.col),
+                max(prev_label.col, label.col) + 1,
+            ):
+                if (r, c) != (prev_label.row, prev_label.col):
+                    p_grid[r][c] = f"\033[93m{grid[r][c]}\033[0m"
+
+        p_grid[label.row][label.col] = f"\033[91m{grid[label.row][label.col]}\033[0m"
+
+        prev_label = label
+
+    p_grid[0][0] = f"\033[92m{grid[0][0]}\033[0m"
+
+    print("\n".join("".join(row) for row in p_grid))
+
+
+def shortest_many_paths(grid: list[list[int]]) -> dict[tuple[int, int], int]:
+    n_rows, n_cols = len(grid), len(grid[0])
+
+    visited: dict[tuple[int, int], tuple[Label, int]] = {}
+
+    queue: list[tuple[int, Label]] = [
+        (0, Label(row=n_rows - 1, col=n_cols - 1, direction="^", count=0))
+    ]
+
+    while queue and len(visited) != n_rows * n_cols:
+        distance, label = heapq.heappop(queue)
+
+        if (label.row, label.col) in visited:
+            continue
+
+        visited[label.row, label.col] = (label, distance)
+
+        for direction, (c_row, c_col, i_direction) in MAPPINGS.items():
+            if label.direction == i_direction:
+                continue
+            else:
+                row, col = (label.row + c_row, label.col + c_col)
+
+            # exclude labels outside the grid or with too many moves in the same
+            # direction
+            if row not in range(0, n_rows) or col not in range(0, n_cols):
+                continue
+
+            heapq.heappush(
+                queue,
+                (
+                    distance
+                    + sum(
+                        grid[r][c]
+                        for r in range(min(row, label.row), max(row, label.row) + 1)
+                        for c in range(min(col, label.col), max(col, label.col) + 1)
+                    )
+                    - grid[row][col],
+                    Label(
+                        row=row,
+                        col=col,
+                        direction=direction,
+                        count=0,
+                        parent=label,
+                    ),
+                ),
+            )
+
+    return {(r, c): visited[r, c][1] for r in range(n_rows) for c in range(n_cols)}
+
+
+def shortest_path(
+    grid: list[list[int]],
+    min_straight: int,
+    max_straight: int,
+    lower_bounds: dict[tuple[int, int], int],
+) -> int:
+    n_rows, n_cols = len(grid), len(grid[0])
+
+    target = (len(grid) - 1, len(grid[0]) - 1)
+
+    # for each tuple (row, col, direction, count), the associated label when visited
+    visited: dict[tuple[int, int, str, int], Label] = {}
+
+    # list of all visited labels for a cell (with associated distance)
+    per_cell: dict[tuple[int, int], list[tuple[Label, int]]] = defaultdict(list)
+
+    # need to add two start labels, otherwise one of the two possible direction will
+    # not be possible
+    queue: list[tuple[int, int, Label]] = [
+        (lower_bounds[0, 0], 0, Label(row=0, col=0, direction="^", count=0)),
+        (lower_bounds[0, 0], 0, Label(row=0, col=0, direction="<", count=0)),
+    ]
+
+    while queue:
+        _, distance, label = heapq.heappop(queue)
+
+        if (label.row, label.col, label.direction, label.count) in visited:
+            continue
+
+        visited[label.row, label.col, label.direction, label.count] = label
+        per_cell[label.row, label.col].append((label, distance))
+
+        if (label.row, label.col) == target:
+            break
+
+        for direction, (c_row, c_col, i_direction) in MAPPINGS.items():
+            # cannot move in the opposite direction
+            if label.direction == i_direction:
+                continue
+
+            # other direction, move 'min_straight' in the new direction
+            elif label.direction != direction:
+                row, col, count = (
+                    label.row + min_straight * c_row,
+                    label.col + min_straight * c_col,
+                    min_straight,
+                )
+
+            # same direction, too many count
+            elif label.count == max_straight:
+                continue
+
+            # same direction, keep going and increment count
+            else:
+                row, col, count = (
+                    label.row + c_row,
+                    label.col + c_col,
+                    label.count + 1,
+                )
+            # exclude labels outside the grid or with too many moves in the same
+            # direction
+            if row not in range(0, n_rows) or col not in range(0, n_cols):
+                continue
+
+            distance_to = (
+                distance
+                + sum(
+                    grid[r][c]
+                    for r in range(min(row, label.row), max(row, label.row) + 1)
+                    for c in range(min(col, label.col), max(col, label.col) + 1)
+                )
+                - grid[label.row][label.col]
+            )
+
+            heapq.heappush(
+                queue,
+                (
+                    distance_to + lower_bounds[row, col],
+                    distance_to,
+                    Label(
+                        row=row,
+                        col=col,
+                        direction=direction,
+                        count=count,
+                        parent=label,
+                    ),
+                ),
+            )
+
+    if VERBOSE:
+        print_shortest_path(grid, target, per_cell)
+
+    return per_cell[target][0][1]
+
+
+data = [[int(c) for c in r] for r in sys.stdin.read().splitlines()]
+estimates = shortest_many_paths(data)
+
+# part 1
+answer_1 = shortest_path(data, 1, 3, lower_bounds=estimates)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = shortest_path(data, 4, 10, lower_bounds=estimates)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2023/day18.py

@@ -0,0 +1,54 @@
+import sys
+from typing import Literal, TypeAlias, cast
+
+Direction: TypeAlias = Literal["R", "L", "U", "D"]
+
+DIRECTIONS: list[Direction] = ["R", "D", "L", "U"]
+MOVES: dict[Direction, tuple[int, int]] = {
+    "R": (0, +1),
+    "L": (0, -1),
+    "U": (-1, 0),
+    "D": (+1, 0),
+}
+
+
+def area(corners: list[tuple[int, int]], perimeter: int) -> int:
+    area = abs(
+        sum(c0[0] * c1[1] - c0[1] * c1[0] for c0, c1 in zip(corners, corners[1::])) // 2
+    )
+    return 1 + area - perimeter // 2 + perimeter
+
+
+def polygon(values: list[tuple[Direction, int]]) -> tuple[list[tuple[int, int]], int]:
+    perimeter = 0
+    corners: list[tuple[int, int]] = [(0, 0)]
+    for direction, amount in values:
+        perimeter += amount
+        corners.append(
+            (
+                corners[-1][0] + amount * MOVES[direction][0],
+                corners[-1][1] + amount * MOVES[direction][1],
+            )
+        )
+    return corners, perimeter
+
+
+lines = sys.stdin.read().splitlines()
+
+
+# part 1
+answer_1 = area(
+    *polygon([(cast(Direction, (p := line.split())[0]), int(p[1])) for line in lines])
+)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = area(
+    *polygon(
+        [
+            (DIRECTIONS[int((h := line.split()[-1])[-2])], int(h[2:-2], 16))
+            for line in lines
+        ]
+    )
+)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2023/day19.py

@@ -0,0 +1,139 @@
+import logging
+import operator
+import os
+import sys
+from math import prod
+from typing import Literal, TypeAlias, cast
+
+VERBOSE = os.getenv("AOC_VERBOSE") == "True"
+
+logging.basicConfig(level=logging.INFO if VERBOSE else logging.WARNING)
+
+Category: TypeAlias = Literal["x", "m", "a", "s"]
+Part: TypeAlias = dict[Category, int]
+PartWithBounds: TypeAlias = dict[Category, tuple[int, int]]
+
+OPERATORS = {"<": operator.lt, ">": operator.gt}
+
+# None if there is no check (last entry), otherwise (category, sense, value)
+Check: TypeAlias = tuple[Category, Literal["<", ">"], int] | None
+
+# workflow as a list of check, in specified order, with target
+Workflow: TypeAlias = list[tuple[Check, str]]
+
+
+def accept(workflows: dict[str, Workflow], part: Part) -> bool:
+    workflow = "in"
+    decision: bool | None = None
+
+    while decision is None:
+        for check, target in workflows[workflow]:
+            passed = check is None
+            if check is not None:
+                category, sense, value = check
+                passed = OPERATORS[sense](part[category], value)
+
+            if passed:
+                if target in workflows:
+                    workflow = target
+                else:
+                    decision = target == "A"
+                break
+
+    return decision
+
+
+def propagate(workflows: dict[str, Workflow], start: PartWithBounds) -> int:
+    def _fmt(meta: PartWithBounds) -> str:
+        return "{" + ", ".join(f"{k}={v}" for k, v in meta.items()) + "}"
+
+    def transfer_or_accept(
+        target: str, meta: PartWithBounds, queue: list[tuple[PartWithBounds, str]]
+    ) -> int:
+        count = 0
+        if target in workflows:
+            logging.info(f"    transfer to {target}")
+            queue.append((meta, target))
+        elif target == "A":
+            count = prod((high - low + 1) for low, high in meta.values())
+            logging.info(f"    accepted ({count})")
+        else:
+            logging.info("    rejected")
+        return count
+
+    accepted = 0
+    queue: list[tuple[PartWithBounds, str]] = [(start, "in")]
+
+    n_iterations = 0
+
+    while queue:
+        n_iterations += 1
+        meta, workflow = queue.pop()
+        logging.info(f"{workflow}: {_fmt(meta)}")
+        for check, target in workflows[workflow]:
+            if check is None:
+                logging.info("  end-of-workflow")
+                accepted += transfer_or_accept(target, meta, queue)
+                continue
+
+            category, sense, value = check
+            bounds, op = meta[category], OPERATORS[sense]
+
+            logging.info(f"  checking {_fmt(meta)} against {category} {sense} {value}")
+
+            if not op(bounds[0], value) and not op(bounds[1], value):
+                logging.info("    reject, always false")
+                continue
+
+            if op(meta[category][0], value) and op(meta[category][1], value):
+                logging.info("    accept, always true")
+                accepted += transfer_or_accept(target, meta, queue)
+                break
+
+            meta2 = meta.copy()
+            low, high = meta[category]
+            if sense == "<":
+                meta[category], meta2[category] = (value, high), (low, value - 1)
+            else:
+                meta[category], meta2[category] = (low, value), (value + 1, high)
+            logging.info(f"    split {_fmt(meta2)} ({target}), {_fmt(meta)}")
+
+            accepted += transfer_or_accept(target, meta2, queue)
+
+    logging.info(f"run took {n_iterations} iterations")
+    return accepted
+
+
+workflows_s, parts_s = sys.stdin.read().strip().split("\n\n")
+
+workflows: dict[str, Workflow] = {}
+for workflow_s in workflows_s.split("\n"):
+    name, block_s = workflow_s.split("{")
+    workflows[name] = []
+
+    for block in block_s[:-1].split(","):
+        check: Check
+        if (i := block.find(":")) >= 0:
+            check, target = (
+                cast(Category, block[0]),
+                cast(Literal["<", ">"], block[1]),
+                int(block[2:i]),
+            ), block[i + 1 :]
+        else:
+            check, target = None, block
+        workflows[name].append((check, target))
+
+# part 1
+parts: list[Part] = [
+    {cast(Category, s[0]): int(s[2:]) for s in part_s[1:-1].split(",")}
+    for part_s in parts_s.split("\n")
+]
+answer_1 = sum(sum(part.values()) for part in parts if accept(workflows, part))
+print(f"answer 1 is {answer_1}")
+
+
+# part 2
+answer_2 = propagate(
+    workflows, {cast(Category, c): (1, 4000) for c in ["x", "m", "a", "s"]}
+)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2023/day2.py

@@ -0,0 +1,43 @@
+import math
+import sys
+from typing import Literal, TypeAlias, cast
+
+CubeType: TypeAlias = Literal["red", "blue", "green"]
+
+MAX_CUBES: dict[CubeType, int] = {"red": 12, "green": 13, "blue": 14}
+
+# parse games
+lines = sys.stdin.read().splitlines()
+games: dict[int, list[dict[CubeType, int]]] = {}
+for line in filter(bool, lines):
+    id_part, sets_part = line.split(":")
+
+    games[int(id_part.split(" ")[-1])] = [
+        {
+            cast(CubeType, s[1]): int(s[0])
+            for cube_draw in cube_set_s.strip().split(", ")
+            if (s := cube_draw.split(" "))
+        }
+        for cube_set_s in sets_part.strip().split(";")
+    ]
+
+# part 1
+answer_1 = sum(
+    id
+    for id, set_of_cubes in games.items()
+    if all(
+        n_cubes <= MAX_CUBES[cube]
+        for cube_set in set_of_cubes
+        for cube, n_cubes in cube_set.items()
+    )
+)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = sum(
+    math.prod(
+        max(cube_set.get(cube, 0) for cube_set in set_of_cubes) for cube in MAX_CUBES
+    )
+    for set_of_cubes in games.values()
+)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2023/day20.py

@@ -0,0 +1,161 @@
+import logging
+import os
+import sys
+from collections import defaultdict
+from math import lcm
+from typing import Literal, TypeAlias
+
+VERBOSE = os.getenv("AOC_VERBOSE") == "True"
+logging.basicConfig(level=logging.INFO if VERBOSE else logging.WARNING)
+
+
+ModuleType: TypeAlias = Literal["broadcaster", "conjunction", "flip-flop"]
+PulseType: TypeAlias = Literal["high", "low"]
+
+modules: dict[str, tuple[ModuleType, list[str]]] = {}
+
+lines = sys.stdin.read().splitlines()
+
+for line in lines:
+    name, outputs_s = line.split(" -> ")
+    outputs = outputs_s.split(", ")
+    if name == "broadcaster":
+        modules["broadcaster"] = ("broadcaster", outputs)
+    else:
+        modules[name[1:]] = (
+            "conjunction" if name.startswith("&") else "flip-flop",
+            outputs,
+        )
+
+
+def process(
+    start: tuple[str, str, PulseType],
+    flip_flop_states: dict[str, Literal["on", "off"]],
+    conjunction_states: dict[str, dict[str, PulseType]],
+) -> tuple[dict[PulseType, int], dict[str, dict[PulseType, int]]]:
+    pulses: list[tuple[str, str, PulseType]] = [start]
+    counts: dict[PulseType, int] = {"low": 0, "high": 0}
+    inputs: dict[str, dict[PulseType, int]] = defaultdict(lambda: {"low": 0, "high": 0})
+
+    logging.info("starting process... ")
+
+    while pulses:
+        input, name, pulse = pulses.pop(0)
+        logging.info(f"{input} -{pulse}-> {name}")
+        counts[pulse] += 1
+
+        inputs[name][pulse] += 1
+
+        if name not in modules:
+            continue
+
+        type, outputs = modules[name]
+
+        if type == "broadcaster":
+            ...
+
+        elif type == "flip-flop":
+            if pulse == "high":
+                continue
+
+            if flip_flop_states[name] == "off":
+                flip_flop_states[name] = "on"
+                pulse = "high"
+            else:
+                flip_flop_states[name] = "off"
+                pulse = "low"
+
+        else:
+            conjunction_states[name][input] = pulse
+
+            if all(state == "high" for state in conjunction_states[name].values()):
+                pulse = "low"
+            else:
+                pulse = "high"
+
+        pulses.extend((name, output, pulse) for output in outputs)
+
+    return counts, inputs
+
+
+with open("./day20.dot", "w") as fp:
+    fp.write("digraph G {\n")
+    fp.write("rx [shape=circle, color=red, style=filled];\n")
+    for name, (type, outputs) in modules.items():
+        if type == "conjunction":
+            shape = "diamond"
+        elif type == "flip-flop":
+            shape = "box"
+        else:
+            shape = "circle"
+        fp.write(f"{name} [shape={shape}];\n")
+    for name, (type, outputs) in modules.items():
+        for output in outputs:
+            fp.write(f"{name} -> {output};\n")
+    fp.write("}\n")
+
+# part 1
+flip_flop_states: dict[str, Literal["on", "off"]] = {
+    name: "off" for name, (type, _) in modules.items() if type == "flip-flop"
+}
+conjunction_states: dict[str, dict[str, PulseType]] = {
+    name: {input: "low" for input, (_, outputs) in modules.items() if name in outputs}
+    for name, (type, _) in modules.items()
+    if type == "conjunction"
+}
+counts: dict[PulseType, int] = {"low": 0, "high": 0}
+for _ in range(1000):
+    result, _ = process(
+        ("button", "broadcaster", "low"), flip_flop_states, conjunction_states
+    )
+    for pulse in ("low", "high"):
+        counts[pulse] += result[pulse]
+answer_1 = counts["low"] * counts["high"]
+print(f"answer 1 is {answer_1}")
+
+# part 2
+
+# reset states
+for name in flip_flop_states:
+    flip_flop_states[name] = "off"
+
+for name in conjunction_states:
+    for input in conjunction_states[name]:
+        conjunction_states[name][input] = "low"
+
+# find the conjunction connected to rx
+to_rx = [name for name, (_, outputs) in modules.items() if "rx" in outputs]
+assert len(to_rx) == 1, "cannot handle multiple module inputs for rx"
+assert (
+    modules[to_rx[0]][0] == "conjunction"
+), "can only handle conjunction as input to rx"
+
+to_rx_inputs = [name for name, (_, outputs) in modules.items() if to_rx[0] in outputs]
+assert all(
+    modules[i][0] == "conjunction" and len(modules[i][1]) == 1 for i in to_rx_inputs
+), "can only handle inversion as second-order inputs to rx"
+
+
+count = 1
+cycles: dict[str, int] = {}
+second: dict[str, int] = {}
+while len(second) != len(to_rx_inputs):
+    _, inputs = process(
+        ("button", "broadcaster", "low"), flip_flop_states, conjunction_states
+    )
+
+    for node in to_rx_inputs:
+        if inputs[node]["low"] == 1:
+            if node not in cycles:
+                cycles[node] = count
+            elif node not in second:
+                second[node] = count
+
+    count += 1
+
+assert all(
+    second[k] == cycles[k] * 2 for k in to_rx_inputs
+), "cannot only handle cycles starting at the beginning"
+
+answer_2 = lcm(*cycles.values())
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2023/day21.py

@@ -0,0 +1,149 @@
+import logging
+import os
+import sys
+
+VERBOSE = os.getenv("AOC_VERBOSE") == "True"
+logging.basicConfig(level=logging.INFO if VERBOSE else logging.WARNING)
+
+
+def reachable(
+    map: list[str], tiles: set[tuple[int, int]], steps: int
+) -> set[tuple[int, int]]:
+    n_rows, n_cols = len(map), len(map[0])
+
+    for _ in range(steps):
+        tiles = {
+            (i + di, j + dj)
+            for i, j in tiles
+            for di, dj in ((-1, 0), (+1, 0), (0, -1), (0, +1))
+            if map[(i + di) % n_rows][(j + dj) % n_cols] != "#"
+        }
+    return tiles
+
+
+map = sys.stdin.read().splitlines()
+start = next(
+    (i, j) for i in range(len(map)) for j in range(len(map[i])) if map[i][j] == "S"
+)
+
+# part 1
+answer_1 = len(reachable(map, {start}, 6 if len(map) < 20 else 64))
+print(f"answer 1 is {answer_1}")
+
+# part 2
+
+# the initial map is a square and contains an empty rhombus whose diameter is the size
+# of the map, and has only empty cells around the middle row and column
+#
+# after ~n/2 steps, the first map is filled with a rhombus, after that we get a bigger
+# rhombus every n steps
+#
+# we are going to find the number of cells reached for the initial rhombus, n steps
+# after and n * 2 steps after
+#
+cycle = len(map)
+rhombus = (len(map) - 3) // 2 + 1
+
+values: list[int] = []
+values.append(len(tiles := reachable(map, {start}, rhombus)))
+values.append(len(tiles := reachable(map, tiles, cycle)))
+values.append(len(tiles := reachable(map, tiles, cycle)))
+
+if logging.root.getEffectiveLevel() == logging.INFO:
+    n_rows, n_cols = len(map), len(map[0])
+
+    rows = [
+        [
+            map[i % n_rows][j % n_cols] if (i, j) not in tiles else "O"
+            for j in range(-2 * cycle, 3 * cycle)
+        ]
+        for i in range(-2 * cycle, 3 * cycle)
+    ]
+
+    for i in range(len(rows)):
+        for j in range(len(rows[i])):
+            if (i // cycle) % 2 == (j // cycle) % 2:
+                rows[i][j] = f"\033[91m{rows[i][j]}\033[0m"
+
+    print("\n".join("".join(row) for row in rows))
+
+
+logging.info(f"values to fit: {values}")
+
+# version 1:
+#
+# after 3 cycles, the figure looks like the following:
+#
+#   I M D
+# I J A K D
+# H A F A L
+# C E A K B
+#   C G B
+#
+# after 4 cycles, the figure looks like the following:
+#
+#     I M D
+#   I J A K D
+# I J A B A K D
+# H A B A B A L
+# C E A B A N F
+#   C E A N F
+#     C G F
+#
+# the 'radius' of the rhombus is the number of cycles minus 1
+#
+# the 4 'corner' (M, H, L, G) are counted once, the blocks with a corner triangle (D, I,
+# C, B) are each counted radius times, the blocks with everything but one corner (J, K,
+# E, N) are each counted radius - 1 times
+#
+# there are two versions of the whole block, A and B in the above (or odd and even),
+# depending on the number of cycles, either A or B will be in the center
+#
+
+counts = [
+    [
+        sum(
+            (i, j) in tiles
+            for i in range(ci * cycle, (ci + 1) * cycle)
+            for j in range(cj * cycle, (cj + 1) * cycle)
+        )
+        for cj in range(-2, 3)
+    ]
+    for ci in range(-2, 3)
+]
+
+radius = (26501365 - rhombus) // cycle - 1
+A = counts[2][2] if radius % 2 == 0 else counts[2][1]
+B = counts[2][2] if radius % 2 == 1 else counts[2][1]
+answer_2 = (
+    (radius + 1) * A
+    + radius * B
+    + 2 * radius * (radius + 1) // 2 * A
+    + 2 * radius * (radius - 1) // 2 * B
+    + sum(counts[i][j] for i, j in ((0, 2), (-1, 2), (2, 0), (2, -1)))
+    + sum(counts[i][j] for i, j in ((0, 1), (0, 3), (-1, 1), (-1, 3))) * (radius + 1)
+    + sum(counts[i][j] for i, j in ((1, 1), (1, 3), (-2, 1), (-2, 3))) * radius
+)
+print(f"answer 2 (v1) is {answer_2}")
+
+# version 2: fitting a polynomial
+#
+# the value we are interested in (26501365) can be written as R + K * C where R is the
+# step at which we find the first rhombus, and K the repeat step, so instead of fitting
+# for X values (R, R + K, R + 2 K), we are going to fit for (0, 1, 2), giving us much
+# simpler equation for the a, b and c coefficient
+#
+# we get:
+#   - (a * 0² + b * 0 + c) = y1  =>  c = y1
+#   - (a * 1² + b * 1 + c) = y2  =>  a + b = y2 - y1
+#                                =>  b = y2 - y1 - a
+#   - (a * 2² + b * 2 + c) = y3  =>  4a + 2b = y3 - y1
+#                                =>  4a + 2(y2 - y1 - a) = y3 - y1
+#                                =>  a = (y1 + y3) / 2 - y2
+#
+y1, y2, y3 = values
+a, b, c = (y1 + y3) // 2 - y2, 2 * y2 - (3 * y1 + y3) // 2, y1
+
+n = (26501365 - rhombus) // cycle
+answer_2 = a * n * n + b * n + c
+print(f"answer 2 (v2) is {answer_2}")

src/holt59/aoc/2023/day22.py

@@ -0,0 +1,111 @@
+import itertools
+import logging
+import os
+import string
+import sys
+from collections import defaultdict
+
+VERBOSE = os.getenv("AOC_VERBOSE") == "True"
+logging.basicConfig(level=logging.INFO if VERBOSE else logging.WARNING)
+
+
+lines = sys.stdin.read().splitlines()
+
+
+def _name(i: int) -> str:
+    if len(lines) < 26:
+        return string.ascii_uppercase[i]
+    return f"B{i:04d}"
+
+
+def build_supports(
+    bricks: list[tuple[tuple[int, int, int], tuple[int, int, int]]]
+) -> tuple[dict[int, set[int]], dict[int, set[int]]]:
+    # 1. compute locations where a brick of sand will land after falling by processing
+    # them in sorted order of bottom z location
+    levels: dict[tuple[int, int, int], int] = defaultdict(lambda: -1)
+    for i_brick, ((sx, sy, sz), (ex, ey, ez)) in enumerate(bricks):
+        assert sx <= ex and sy <= ey and sz <= ez
+
+        xs, ys = range(sx, ex + 1), range(sy, ey + 1)
+
+        for z in range(sz - 1, 0, -1):
+            if any(levels[x, y, z] >= 0 for x, y in itertools.product(xs, ys)):
+                break
+            sz, ez = sz - 1, ez - 1
+
+        bricks[i_brick] = ((sx, sy, sz), (ex, ey, ez))
+        zs = range(sz, ez + 1)
+
+        for x, y, z in itertools.product(xs, ys, zs):
+            levels[x, y, z] = i_brick
+
+    # 2. compute the bricks that supports any brick
+    supported_by: dict[int, set[int]] = {}
+    supports: dict[int, set[int]] = {i_brick: set() for i_brick in range(len(bricks))}
+    for i_brick, ((sx, sy, sz), (ex, ey, ez)) in enumerate(bricks):
+        name = _name(i_brick)
+
+        supported_by[i_brick] = {
+            v
+            for x, y in itertools.product(range(sx, ex + 1), range(sy, ey + 1))
+            if (v := levels[x, y, sz - 1]) != -1
+        }
+        logging.info(
+            f"{name} supported by {', '.join(map(_name, supported_by[i_brick]))}"
+        )
+
+        for support in supported_by[i_brick]:
+            supports[support].add(i_brick)
+
+    return supported_by, supports
+
+
+bricks: list[tuple[tuple[int, int, int], tuple[int, int, int]]] = []
+for line in lines:
+    bricks.append(
+        (
+            tuple(int(c) for c in line.split("~")[0].split(",")),  # type: ignore
+            tuple(int(c) for c in line.split("~")[1].split(",")),  # type: ignore
+        )
+    )
+
+# sort bricks by bottom z position to compute supports
+bricks = sorted(bricks, key=lambda b: b[0][-1])
+supported_by, supports = build_supports(bricks)
+
+# part 1
+answer_1 = len(bricks) - sum(
+    any(len(supported_by[supported]) == 1 for supported in supports_to)
+    for supports_to in supports.values()
+)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+falling_in_chain: dict[int, set[int]] = {}
+for i_brick in range(len(bricks)):
+    to_disintegrate: set[int] = {
+        supported
+        for supported in supports[i_brick]
+        if len(supported_by[supported]) == 1
+    }
+
+    supported_by_copy = dict(supported_by)
+
+    falling_in_chain[i_brick] = set()
+    while to_disintegrate:
+        falling_in_chain[i_brick].update(to_disintegrate)
+
+        to_disintegrate_v: set[int] = set()
+
+        for d_brick in to_disintegrate:
+            for supported in supports[d_brick]:
+                supported_by_copy[supported] = supported_by_copy[supported] - {d_brick}
+
+                if not supported_by_copy[supported]:
+                    to_disintegrate_v.add(supported)
+
+        to_disintegrate = to_disintegrate_v
+
+answer_2 = sum(len(falling) for falling in falling_in_chain.values())
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2023/day23.py

@@ -0,0 +1,157 @@
+import logging
+import os
+import sys
+from collections import defaultdict
+
+VERBOSE = os.getenv("AOC_VERBOSE") == "True"
+logging.basicConfig(level=logging.INFO if VERBOSE else logging.WARNING)
+
+Direction = {
+    ">": (0, +1),
+    "<": (0, -1),
+    "^": (-1, 0),
+    "v": (+1, 0),
+}
+
+Neighbors = {".": ((+1, 0), (-1, 0), (0, +1), (0, -1)), "#": ()} | {
+    k: (v,) for k, v in Direction.items()
+}
+
+
+def neighbors(
+    grid: list[str], node: tuple[int, int], ignore: set[tuple[int, int]] = set()
+):
+    """
+    Compute neighbors of the given node, ignoring the given set of nodes and considering
+    that you can go uphill on slopes.
+    """
+    i, j = node
+
+    for di, dj in Neighbors[grid[i][j]]:
+        ti, tj = di + i, dj + j
+
+        if ti < 0 or ti >= n_rows or tj < 0 or tj >= n_cols:
+            continue
+
+        if (ti, tj) in ignore:
+            continue
+
+        v = grid[ti][tj]
+
+        if (
+            v == "#"
+            or (v == "v" and di == -1)
+            or (v == "^" and di == 1)
+            or (v == ">" and dj == -1)
+            or (v == "<" and dj == 1)
+        ):
+            continue
+
+        yield ti, tj
+
+
+def reachable(
+    grid: list[str], start: tuple[int, int], target: tuple[int, int]
+) -> tuple[tuple[int, int], int]:
+    """
+    Compute the next 'reachable' node in the grid, starting at the given node.
+
+    The next 'reachable' node is the first node after a slope in the path starting from
+    the given node (not going uphill).
+    """
+    distance, path = 0, {start}
+    while True:
+        i, j = start
+
+        if (i, j) == target:
+            return (target, distance)
+
+        if grid[i][j] != ".":
+            di, dj = Direction[grid[i][j]]
+            return ((i + di, j + dj), distance + 1)
+
+        start = next(neighbors(grid, start, path := path | {(i, j)}))
+        distance += 1
+
+
+def compute_direct_links(
+    grid: list[str], start: tuple[int, int], target: tuple[int, int]
+) -> dict[tuple[int, int], list[tuple[tuple[int, int], int]]]:
+    if start == target:
+        return {}
+
+    direct: dict[tuple[int, int], list[tuple[tuple[int, int], int]]] = {start: []}
+    for neighbor in neighbors(grid, start):
+        i, j = neighbor
+        di, dj = Direction[grid[i][j]]
+
+        reach, distance = reachable(lines, (i + di, j + dj), target)
+        direct[start].append((reach, distance + 2))
+
+        direct.update(compute_direct_links(grid, reach, target))
+
+    return direct
+
+
+def longest_path_length(
+    links: dict[tuple[int, int], list[tuple[tuple[int, int], int]]],
+    start: tuple[int, int],
+    target: tuple[int, int],
+) -> int:
+    max_distance: int = -1
+    queue: list[tuple[tuple[int, int], int, frozenset[tuple[int, int]]]] = [
+        (start, 0, frozenset({start}))
+    ]
+
+    nodes = 0
+    while queue:
+        node, distance, path = queue.pop()
+
+        nodes += 1
+
+        if node == target:
+            max_distance = max(distance, max_distance)
+            continue
+
+        queue.extend(
+            (reach, distance + length, path | {reach})
+            for reach, length in links.get(node, [])
+            if reach not in path
+        )
+
+    logging.info(f"processed {nodes} nodes")
+
+    return max_distance
+
+
+lines = sys.stdin.read().splitlines()
+n_rows, n_cols = len(lines), len(lines[0])
+start = (0, 1)
+target = (len(lines) - 1, len(lines[0]) - 2)
+
+
+direct_links: dict[tuple[int, int], list[tuple[tuple[int, int], int]]] = {
+    start: [reachable(lines, start, target)]
+}
+direct_links.update(compute_direct_links(lines, direct_links[start][0][0], target))
+
+# part 1
+answer_1 = longest_path_length(direct_links, start, target)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+reverse_links: dict[tuple[int, int], list[tuple[tuple[int, int], int]]] = defaultdict(
+    list
+)
+for origin, links in direct_links.items():
+    for destination, distance in links:
+        if origin != start:
+            reverse_links[destination].append((origin, distance))
+
+links = {
+    k: direct_links.get(k, []) + reverse_links.get(k, [])
+    for k in direct_links.keys() | reverse_links.keys()
+}
+
+answer_2 = longest_path_length(links, start, target)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2023/day24.py

@@ -0,0 +1,63 @@
+import sys
+
+import numpy as np
+from sympy import solve, symbols
+
+lines = sys.stdin.read().splitlines()
+
+positions = np.array(
+    [[int(c) for c in line.split("@")[0].strip().split(", ")] for line in lines]
+)
+velocities = np.array(
+    [[int(c) for c in line.split("@")[1].strip().split(", ")] for line in lines]
+)
+
+# part 1
+low, high = [7, 27] if len(positions) <= 10 else [200000000000000, 400000000000000]
+
+count = 0
+for i1, (p1, v1) in enumerate(zip(positions, velocities)):
+    p, r = p1[:2], v1[:2]
+
+    q, s = positions[i1 + 1 :, :2], velocities[i1 + 1 :, :2]
+
+    rs = np.cross(r, s)
+
+    q, s, rs = q[m := (rs != 0)], s[m], rs[m]
+    t = np.cross((q - p), s) / rs
+    u = np.cross((q - p), r) / rs
+
+    t, u = t[m := ((t >= 0) & (u >= 0))], u[m]
+    c = p + np.expand_dims(t, 1) * r
+    count += np.all((low <= c) & (c <= high), axis=1).sum()
+
+
+answer_1 = count
+print(f"answer 1 is {answer_1}")
+
+# part 2
+# equation
+#   p1 + t1 * v1 == p0 + t1 * v0
+#   p2 + t2 * v2 == p0 + t2 * v0
+#   p3 + t3 * v3 == p0 + t3 * v0
+#      ...
+#   pn + tn * vn == p0 + tn * v0
+#
+
+# we can solve with only 3 lines since each lines contains 3
+# equations (x / y / z), so 3 lines give 9 equations and 9
+# variables: position (3), velocities (3) and times (3).
+n = 3
+
+x, y, z, vx, vy, vz, *ts = symbols(
+    "x y z vx vy vz " + " ".join(f"t{i}" for i in range(n + 1))
+)
+equations = []
+for i1, ti in zip(range(n), ts):
+    for p, d, pi, di in zip((x, y, z), (vx, vy, vz), positions[i1], velocities[i1]):
+        equations.append(p + ti * d - pi - ti * di)
+
+r = solve(equations, [x, y, z, vx, vy, vz] + list(ts), dict=True)[0]
+
+answer_2 = r[x] + r[y] + r[z]
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/2023/day25.py

@@ -0,0 +1,25 @@
+import sys
+
+import networkx as nx
+
+components = {
+    (p := line.split(": "))[0]: p[1].split() for line in sys.stdin.read().splitlines()
+}
+
+targets = {t for c in components for t in components[c] if t not in components}
+
+graph = nx.Graph()
+graph.add_edges_from((u, v) for u, vs in components.items() for v in vs)
+
+cut = nx.minimum_edge_cut(graph)
+graph.remove_edges_from(cut)
+
+c1, c2 = nx.connected_components(graph)
+
+# part 1
+answer_1 = len(c1) * len(c2)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+answer_2 = ...
+print(f"answer 2 is {answer_2}")