2015: d13: ex2: add solution

2015/d13/ex2/ex2.py

@@ -0,0 +1,47 @@
+#!/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)
+        )
+
+    def add_me(deltas: dict[str, dict[str, int]]) -> None:
+        deltas["me"] = {}
+        for other in deltas.keys():
+            deltas["me"][other] = 0
+            deltas[other]["me"] = 0
+
+    deltas = parse(input)
+    add_me(deltas)
+    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()