Add solution to 2025-12-11

Author: fuglede

2025/day11/solutions.py

@@ -0,0 +1,22 @@
+from functools import cache
+
+with open("input") as f:
+    ls = [l.split() for l in f.read().splitlines()]
+
+succ = {start[:-1]: to for start, *to in ls}
+
+
+@cache
+def paths_from(node, dac_seen=True, fft_seen=True):
+    dac_seen = dac_seen or node == "dac"
+    fft_seen = fft_seen or node == "fft"
+    if node == "out":
+        return dac_seen and fft_seen
+    return sum(paths_from(to_node, dac_seen, fft_seen) for to_node in succ[node])
+
+
+# Part 1
+print(paths_from("you"))
+
+# Part 2
+print(paths_from("svr", False, False))