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-rwxr-xr-x2025/07/puzzle-2.py31
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diff --git a/2025/07/puzzle-2.py b/2025/07/puzzle-2.py
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+#!/usr/bin/python3
+
+import collections
+import functools
+
+
+Pos = collections.namedtuple('Pos', ['x', 'y'])
+
+
+def main() -> None:
+ with open('input', 'r') as f:
+ grid = tuple(tuple(x.strip()) for x in f.readlines())
+
+ pos = Pos(grid[0].index('S'), 0)
+ print(npaths(grid, pos))
+
+
+@functools.cache
+def npaths(grid: list[list[str]], pos: Pos) -> int:
+ if pos.y == len(grid):
+ return 1
+ if grid[pos.y][pos.x] == '^':
+ return (
+ npaths(grid, Pos(pos.x - 1, pos.y))
+ + npaths(grid, Pos(pos.x + 1, pos.y))
+ )
+ return npaths(grid, Pos(pos.x, pos.y + 1))
+
+
+if __name__ == '__main__':
+ main()