Add initial input data for Day 11 of 2025 challenge

2025/day11.py

@@ -0,0 +1,63 @@
+"""Day 11: Advent of Code 2025."""
+
+import time
+from collections import defaultdict
+from aoc import read_lines
+
+
+def build_graph(data: list[str]) -> dict[str, set[str]]:
+    """Build graph from input: 'fxp: udl vii hgb qmy' -> adjacency dict."""
+    graph = defaultdict(set)
+    for line in data:
+        node, neighbors = line.split(': ')
+        for neighbor in neighbors.split():
+            graph[node].add(neighbor)
+            
+    return graph
+
+def count_paths(node, target, graph, memo={}):
+      if node == target:
+          return 1
+      if node in memo:
+          return memo[node]
+
+      total = 0
+      for neighbor in graph[node]:
+          total += count_paths(neighbor, target, graph, memo)
+
+      memo[node] = total
+      return total
+
+def part1(data):
+    """Solve part 1."""
+    graph = build_graph(data)
+    count = count_paths("you", "out", graph)
+    return count
+
+
+def part2(data):
+    """Solve part 2."""
+    graph = build_graph(data)
+    c1 = count_paths("svr", "dac", graph, {})
+    c2 = count_paths("dac", "fft", graph, {})
+    c3 = count_paths("fft", "out", graph, {})
+    c4 = count_paths("svr", "fft", graph, {})
+    c5 = count_paths("fft", "dac", graph, {})
+    c6 = count_paths("dac", "out", graph, {})
+
+    return (c1 * c2* c3) + (c4*c5*c6)
+
+
+if __name__ == "__main__":
+    DAY = 11
+    data = read_lines(DAY)
+
+    t0 = time.perf_counter()
+    p1 = part1(data)
+    t1 = time.perf_counter()
+    print(f"Part 1: {p1}  ({(t1-t0)*1000:.2f} ms)")
+
+    t0 = time.perf_counter()
+    p2 = part2(data)
+    t1 = time.perf_counter()
+    print(f"Part 2: {p2}  ({(t1-t0)*1000:.2f} ms)")