From 34aaa729d6d68b222e68dd895f1b2dcbdc6d371a Mon Sep 17 00:00:00 2001
From: Bruno BELANYI <bruno@belanyi.fr>
Date: Wed, 21 May 2025 03:48:12 +0100
Subject: [PATCH] 2015: d13: ex1: add solution

---
 2015/d13/ex1/ex1.py | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100755 2015/d13/ex1/ex1.py

diff --git a/2015/d13/ex1/ex1.py b/2015/d13/ex1/ex1.py
new file mode 100755
index 0000000..06ac1ad
--- /dev/null
+++ b/2015/d13/ex1/ex1.py
@@ -0,0 +1,40 @@
+#!/usr/bin/env python
+
+import collections
+import itertools
+import sys
+
+
+def solve(input: str) -> int:
+    def parse_line(input: str) -> tuple[str, str, int]:
+        split_input = input.removesuffix(".").split()
+        p, other = split_input[0], split_input[-1]
+        delta = int(split_input[3]) * (1 if split_input[2] == "gain" else -1)
+        return p, other, delta
+
+    def parse(input: str) -> dict[str, dict[str, int]]:
+        res: dict[str, dict[str, int]] = collections.defaultdict(dict)
+        for p, neighbour, delta in map(parse_line, input.splitlines()):
+            res[p][neighbour] = delta
+        return res
+
+    def score_seating(deltas: dict[str, dict[str, int]], seating: list[str]) -> int:
+        table = itertools.chain(seating, [seating[0]])
+        return sum(
+            deltas[p1][p2] + deltas[p2][p1] for p1, p2 in itertools.pairwise(table)
+        )
+
+    deltas = parse(input)
+    return max(
+        score_seating(deltas, list(perm))
+        for perm in itertools.permutations(deltas.keys())
+    )
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()