From 00000240ea5dcfc40da35d5f3e97a364e50c82bf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Matej=20Jane=C5=BEi=C4=8D?= <janezic.mj@gmail.com>
Date: Fri, 12 Dec 2025 13:01:13 +0100
Subject: [PATCH] feat: add solution 2025/11

---
 data/example/2025/11.txt         | 15 ++++++
 src/solution/year_2025/day_11.py | 86 ++++++++++++++++++++++++++++++++
 2 files changed, 101 insertions(+)
 create mode 100644 data/example/2025/11.txt
 create mode 100644 src/solution/year_2025/day_11.py

diff --git a/data/example/2025/11.txt b/data/example/2025/11.txt
new file mode 100644
index 000000000..f03555a
--- /dev/null
+++ b/data/example/2025/11.txt
@@ -0,0 +1,15 @@
+aaa: you hhh
+you: bbb ccc
+bbb: ddd eee
+ccc: ddd eee fff
+ddd: ggg
+eee: out
+fff: out
+ggg: out
+hhh: ccc fff iii
+iii: out
+svr: zzz www
+zzz: dac
+dac: www out fft
+fft: out
+www: out
diff --git a/src/solution/year_2025/day_11.py b/src/solution/year_2025/day_11.py
new file mode 100644
index 000000000..9c896e3
--- /dev/null
+++ b/src/solution/year_2025/day_11.py
@@ -0,0 +1,86 @@
+import collections
+import functools
+from typing import Any
+
+
+def _parse_input(input_data: str) -> tuple[dict[str, int], dict[int, list[int]]]:
+    counter = 0
+    ids = {}
+
+    graph = collections.defaultdict(list)
+
+    for line in input_data.splitlines():
+        node, _neighs = line.split(": ")
+        neighs = _neighs.split()
+
+        if node not in ids:
+            ids[node] = counter
+            counter += 1
+
+        for n in filter(lambda x: x not in ids, neighs):
+            ids[n] = counter
+            counter += 1
+
+        for n in neighs:
+            graph[ids[n]].append(ids[node])
+
+    return ids, graph
+
+
+def _count_paths(
+    graph: dict[int, list[int]],
+    start: int,
+    end: int,
+    skip: set[int] | None = None,
+) -> int:
+    if skip is None:
+        skip = set()
+
+    @functools.cache
+    def traverse(node: int):
+        if node in skip:
+            return 0
+        if node == start:
+            return 1
+        return sum(traverse(n) for n in graph[node])
+
+    return traverse(end)
+
+
+def part_1(input_data: str) -> Any:
+    ids, graph = _parse_input(input_data)
+    print(graph)
+
+    you = ids["you"]
+    out = ids["out"]
+
+    return _count_paths(graph, you, out)
+
+
+def part_2(input_data: str) -> Any:
+    ids, graph = _parse_input(input_data)
+
+    svr = ids["svr"]
+    out = ids["out"]
+
+    dac = ids["dac"]
+    fft = ids["fft"]
+
+    svr_dac = _count_paths(graph, svr, dac, {out, fft})
+    svr_fft = _count_paths(graph, svr, fft, {out, dac})
+
+    dac_fft = _count_paths(graph, dac, fft, {out})
+    fft_dac = _count_paths(graph, fft, dac, {out})
+
+    dac_out = _count_paths(graph, dac, out, {fft})
+    fft_out = _count_paths(graph, fft, out, {dac})
+
+    return svr_dac * dac_fft * fft_out + svr_fft * fft_dac * dac_out
+
+
+def test_part_1(example_data):
+    assert part_1(example_data) == 5
+
+
+def test_part_2(example_data):
+    assert part_2(example_data) == 1