Refactor 2024 day 6 to be a little bit faster.
All checks were successful
continuous-integration/drone/push Build is passing

This commit is contained in:
Mikael CAPELLE 2024-12-06 09:55:08 +01:00
parent f9a3dee20b
commit 1caf93b38b
2 changed files with 87 additions and 59 deletions

View File

@ -9,7 +9,7 @@ def in_correct_order(update: list[int], requirements: dict[int, set[int]]) -> bo
) )
def fix_order( def to_correct_order(
update: list[int], update: list[int],
requirements: dict[int, set[int]], requirements: dict[int, set[int]],
max_update_length: int | None = None, max_update_length: int | None = None,
@ -39,7 +39,7 @@ def fix_order(
return update return update
part1, part2 = sys.stdin.read().split("\n\n") part1, part2 = sys.stdin.read().strip().split("\n\n")
requirements: dict[int, set[int]] = defaultdict(set) requirements: dict[int, set[int]] = defaultdict(set)
for line in part1.splitlines(): for line in part1.splitlines():
@ -55,7 +55,7 @@ answer_1 = sum(
) )
answer_2 = sum( answer_2 = sum(
fix_order(update, requirements, len(update) // 2 + 1)[-1] to_correct_order(update, requirements, len(update) // 2 + 1)[-1]
for update in updates for update in updates
if not in_correct_order(update, requirements) if not in_correct_order(update, requirements)
) )

View File

@ -1,29 +1,94 @@
import itertools as it
import sys import sys
from typing import TypeAlias from typing import TypeAlias
NodeType: TypeAlias = tuple[tuple[int, int], tuple[int, int]]
EdgesType: TypeAlias = dict[NodeType, tuple[NodeType, set[tuple[int, int]]]]
ROTATE = {(-1, 0): (0, 1), (0, 1): (1, 0), (1, 0): (0, -1), (0, -1): (-1, 0)}
START_NODE: NodeType = ((-2, -2), (-1, 0))
FINAL_POS: tuple[int, int] = (-1, -1)
def move( def move(
lines: list[str], pos: tuple[int, int], dir: tuple[int, int] lines: list[str], pos: tuple[int, int], dir: tuple[int, int]
) -> tuple[tuple[int, int] | None, list[tuple[int, int]]]: ) -> tuple[tuple[int, int] | None, set[tuple[int, int]]]:
n_rows, n_cols = len(lines), len(lines[0]) n_rows, n_cols = len(lines), len(lines[0])
row, col = pos row, col = pos
marked: list[tuple[int, int]] = []
marked: set[tuple[int, int]] = set()
final_pos: tuple[int, int] | None = None
while True: while True:
marked.append((row, col)) marked.add((row, col))
if not (0 <= row + dir[0] < n_rows and 0 <= col + dir[1] < n_cols): if not (0 <= row + dir[0] < n_rows and 0 <= col + dir[1] < n_cols):
pos = None final_pos = None
break break
if lines[row + dir[0]][col + dir[1]] != ".": if lines[row + dir[0]][col + dir[1]] != ".":
pos = (row, col) final_pos = (row, col)
break break
row += dir[0] row += dir[0]
col += dir[1] col += dir[1]
return pos, marked return final_pos, marked
def compute_graph(lines: list[str], start_node: NodeType):
n_rows, n_cols = len(lines), len(lines[0])
edges: EdgesType = {}
start_pos, start_dir = start_node
end_pos, marked = move(lines, start_pos, start_dir)
assert end_pos is not None
edges[START_NODE] = ((end_pos, start_dir), marked)
for row, col in it.product(range(n_rows), range(n_cols)):
if lines[row][col] != "#":
continue
for start_pos, start_dir in (
((row - 1, col), (1, 0)),
((row + 1, col), (-1, 0)),
((row, col - 1), (0, 1)),
((row, col + 1), (0, -1)),
):
if 0 <= start_pos[0] < n_rows and 0 <= start_pos[1] < n_cols:
end_pos, marked = move(lines, start_pos, ROTATE[start_dir])
edges[start_pos, start_dir] = (
(end_pos or FINAL_POS, ROTATE[start_dir]),
marked,
)
return edges
def is_loop(lines: list[str], edges: EdgesType, position: tuple[int, int]):
row, col = position
current_node = START_NODE
found: set[NodeType] = set()
while current_node[0] != FINAL_POS and current_node not in found:
found.add(current_node)
target_node, edge_marked = edges[current_node]
if (row, col) in edge_marked:
# need to break the edge
target_dir = target_node[1]
end_pos, _ = move(
lines, (row - target_dir[0], col - target_dir[1]), ROTATE[target_dir]
)
current_node = (end_pos or FINAL_POS, ROTATE[target_dir])
else:
current_node = target_node
return current_node in found
def print_grid( def print_grid(
@ -42,65 +107,28 @@ def print_grid(
print() print()
ROTATE = {(-1, 0): (0, 1), (0, 1): (1, 0), (1, 0): (0, -1), (0, -1): (-1, 0)} # read lines
lines = sys.stdin.read().splitlines() lines = sys.stdin.read().splitlines()
n_rows, n_cols = len(lines), len(lines[0])
# find and delete original position
start_pos = next( start_pos = next(
(i, j) for i in range(n_rows) for j in range(n_cols) if lines[i][j] == "^" (i, j) for i, row in enumerate(lines) for j, col in enumerate(row) if col == "^"
) )
lines[start_pos[0]] = lines[start_pos[0]].replace("^", ".") lines[start_pos[0]] = lines[start_pos[0]].replace("^", ".")
# compute edges from the map
edges = compute_graph(lines, (start_pos, (-1, 0)))
# part 1 # part 1
marked: set[tuple[int, int]] = set() marked: set[tuple[int, int]] = set()
current_node = START_NODE
current_pos: tuple[int, int] | None = start_pos while current_node[0] != FINAL_POS:
current_dir = (-1, 0) current_node, current_marked = edges[current_node]
marked = marked.union(current_marked)
while current_pos is not None:
# print_grid(lines, marked, current_pos)
new_pos, new_marked = move(lines, current_pos, current_dir)
marked = marked.union(new_marked)
current_pos = new_pos
current_dir = ROTATE[current_dir]
# print_grid(lines, marked, current_pos)
answer_1 = len(marked) answer_1 = len(marked)
answer_2 = 0
for row in range(n_rows):
for col in range(n_cols):
if (row, col) == start_pos or lines[row][col] != ".":
continue
chars = list(map(list, lines))
chars[row][col] = "#"
current_pos = start_pos
current_dir = (-1, 0)
found: set[tuple[tuple[int, int], tuple[int, int]]] = set()
while current_pos is not None:
if current_pos != start_pos:
found.add((current_pos, current_dir))
new_pos, new_marked = move(
["".join(line) for line in chars], current_pos, current_dir
)
current_pos = new_pos
current_dir = ROTATE[current_dir]
if (current_pos, current_dir) in found:
print(row, col)
answer_2 += 1
break
print(f"answer 1 is {answer_1}") print(f"answer 1 is {answer_1}")
answer_2 = sum(is_loop(lines, edges, pos) for pos in marked if pos != start_pos)
print(f"answer 2 is {answer_2}") print(f"answer 2 is {answer_2}")