Add 2025 day 7 solutionsHEADmaster

1 files changed, 31 insertions, 0 deletions

diff --git a/2025/07/puzzle-2.py b/2025/07/puzzle-2.py
new file mode 100755
index 0000000..3695889
--- /dev/null
+++ b/2025/07/puzzle-2.py
@@ -0,0 +1,31 @@
+#!/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()