2015 day 22, part 1.

src/holt59/aoc/2015/day22.py

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+from __future__ import annotations
+
+import heapq
+import sys
+from typing import Literal, TypeAlias
+
+PlayerType: TypeAlias = Literal["player", "boss"]
+SpellType: TypeAlias = Literal["magic missile", "drain", "shield", "poison", "recharge"]
+BuffType: TypeAlias = Literal["shield", "poison", "recharge"]
+Node: TypeAlias = tuple[
+    PlayerType,
+    int,
+    int,
+    int,
+    int,
+    int,
+    tuple[tuple[BuffType, int], ...],
+    tuple[tuple[SpellType, int], ...],
+]
+
+
+def play(
+    player_hp: int,
+    player_mana: int,
+    player_armor: int,
+    boss_hp: int,
+    boss_attack: int,
+    hard_mode: bool,
+) -> tuple[tuple[SpellType, int], ...]:
+    winning_node: tuple[tuple[SpellType, int], ...] | None = None
+
+    visited: set[
+        tuple[PlayerType, int, int, int, int, tuple[tuple[BuffType, int], ...]]
+    ] = set()
+    nodes: list[Node] = [
+        ("player", 0, player_hp, player_mana, player_armor, boss_hp, (), ())
+    ]
+
+    while winning_node is None:
+        (
+            player,
+            mana,
+            player_hp,
+            player_mana,
+            player_armor,
+            boss_hp,
+            buffs,
+            spells,
+        ) = heapq.heappop(nodes)
+
+        if (player, player_hp, player_mana, player_armor, boss_hp, buffs) in visited:
+            continue
+
+        visited.add((player, player_hp, player_mana, player_armor, boss_hp, buffs))
+
+        if hard_mode and player == "player":
+            player_hp = max(0, player_hp - 1)
+
+        if player_hp == 0:
+            continue
+
+        if boss_hp == 0:
+            winning_node = spells
+            continue
+
+        new_buffs: list[tuple[BuffType, int]] = []
+        for buff, length in buffs:
+            length = length - 1
+            match buff:
+                case "poison":
+                    boss_hp = max(boss_hp - 3, 0)
+                case "shield":
+                    if length == 0:
+                        player_armor -= 7
+                case "recharge":
+                    player_mana += 101
+
+            if length > 0:
+                new_buffs.append((buff, length))
+
+        buffs = tuple(new_buffs)
+
+        if player == "boss":
+            heapq.heappush(
+                nodes,
+                (
+                    "player",
+                    mana,
+                    max(0, player_hp - max(boss_attack - player_armor, 1)),
+                    player_mana,
+                    player_armor,
+                    boss_hp,
+                    buffs,
+                    spells,
+                ),
+            )
+        else:
+            buff_types = {b for b, _ in buffs}
+
+            for spell, cost, damage, regeneration in (
+                ("magic missile", 53, 4, 0),
+                ("drain", 73, 2, 2),
+            ):
+                if player_mana < cost:
+                    continue
+
+                heapq.heappush(
+                    nodes,
+                    (
+                        "boss",
+                        mana + cost,
+                        player_hp + regeneration,
+                        player_mana - cost,
+                        player_armor,
+                        max(0, boss_hp - damage),
+                        buffs,
+                        spells + ((spell, cost),),
+                    ),
+                )
+
+            for buff_type, buff_cost, buff_length in (
+                ("shield", 113, 6),
+                ("poison", 173, 6),
+                ("recharge", 229, 5),
+            ):
+                if buff_type in buff_types:
+                    continue
+
+                if player_mana < buff_cost:
+                    continue
+
+                heapq.heappush(
+                    nodes,
+                    (
+                        "boss",
+                        mana + buff_cost,
+                        player_hp,
+                        player_mana - buff_cost,
+                        player_armor + 7 * (buff_type == "shield"),
+                        boss_hp,
+                        buffs + ((buff_type, buff_length),),
+                        spells + ((buff_type, buff_cost),),
+                    ),
+                )
+
+    return winning_node
+
+
+lines = sys.stdin.read().splitlines()
+
+player_hp = 50
+player_mana = 500
+player_armor = 0
+
+boss_hp = int(lines[0].split(":")[1].strip())
+boss_attack = int(lines[1].split(":")[1].strip())
+
+answer_1 = sum(
+    c
+    for _, c in play(player_hp, player_mana, player_armor, boss_hp, boss_attack, False)
+)
+print(f"answer 1 is {answer_1}")
+
+# 1242 (not working)
+answer_2 = sum(
+    c for _, c in play(player_hp, player_mana, player_armor, boss_hp, boss_attack, True)
+)
+print(f"answer 2 is {answer_2}")

src/holt59/aoc/inputs/holt59/2015/day22.txt

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+Hit Points: 51
+Damage: 9