2025: d10: ex1: add solution

2025/d10/ex1/ex1.py

@@ -0,0 +1,65 @@
+#!/usr/bin/env python
+
+import itertools
+import sys
+from typing import NamedTuple
+
+
+class Machine(NamedTuple):
+    lights: tuple[bool, ...]
+    buttons: list[list[int]]
+    joltage: list[int]
+
+    @classmethod
+    def from_str(cls, input: str) -> "Machine":
+        raw_lights, *raw_buttons, raw_joltage = input.split()
+        lights = [c == "#" for c in raw_lights[1:-1]]
+        buttons = [[int(n) for n in button[1:-1].split(",")] for button in raw_buttons]
+        joltage = [int(n) for n in raw_joltage[1:-1].split(",")]
+        return cls(tuple(lights), buttons, joltage)
+
+
+def solve(input: list[str]) -> int:
+    def parse(input: list[str]) -> list[Machine]:
+        return [Machine.from_str(line) for line in input]
+
+    def apply_schematic(
+        lights: tuple[bool, ...],
+        button: list[int],
+    ) -> tuple[bool, ...]:
+        assert all(n < len(lights) for n in button)  # Sanity check
+        return tuple((l if i not in button else not l) for i, l in enumerate(lights))
+
+    def start_presses(machine: Machine) -> int:
+        start = tuple(False for _ in machine.lights)
+        queue = [start]
+        seen = {start}
+        for i in itertools.count(1):
+            new_queue: list[tuple[bool, ...]] = []
+            for p in queue:
+                for button in machine.buttons:
+                    n = apply_schematic(p, button)
+                    # If we've seen `n` before, it was in less or equal number of steps
+                    if n in seen:
+                        continue
+                    # If we're at the end state, we've found the fastest path
+                    if n == machine.lights:
+                        return i
+                    # Else, explore from that state
+                    new_queue.append(n)
+                    seen.add(n)
+            assert new_queue  # Sanity check
+            queue = new_queue
+        assert False  # Sanity check
+
+    manual = parse(input)
+    return sum(start_presses(machine) for machine in manual)
+
+
+def main() -> None:
+    input = sys.stdin.read().splitlines()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()