2015: d24: ex1: add solution

2015/d24/ex1/ex1.py

@@ -0,0 +1,46 @@
+#!/usr/bin/env python
+
+import itertools
+import math
+import sys
+
+
+def solve(input: str) -> int:
+    def parse(input: str) -> list[int]:
+        return [int(n) for n in input.splitlines()]
+
+    def package_groups(packages: list[int]) -> tuple[list[int], list[int], list[int]]:
+        assert sum(packages) % 3 == 0  # Sanity check
+        target_weight = sum(packages) // 3
+
+        # I'm lazy, a brute-force double loop is good enough
+        for first_len in range(1, len(packages) + 1):
+            for perm in itertools.combinations(range(len(packages)), first_len):
+                first = [packages[p] for p in perm]
+                if sum(first) != target_weight:
+                    continue
+                others = [p for i, p in enumerate(packages) if i not in perm]
+                for sec_len in range(1, len(others) + 1):
+                    for perm in itertools.combinations(range(len(others)), sec_len):
+                        second = [others[p] for p in perm]
+                        if sum(second) != target_weight:
+                            continue
+                        last = [p for i, p in enumerate(others) if i not in perm]
+                        return first, second, last
+        assert False  # Sanity check
+
+    def quantum_entanglement(packages: list[int]) -> int:
+        return math.prod(packages)
+
+    packages = parse(input)
+    best_split = package_groups(packages)
+    return quantum_entanglement(best_split[0])
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()