2025 08

Python/2025/08/main.py

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+import bisect, math
+from itertools import combinations
+input = open("input", 'r')
+
+points = []
+for line in input:
+    points.append(tuple((int(cord) for cord in line.split(","))))
+
+# distances = []
+# distance_key = lambda d: d[0]
+# for i, p in enumerate(points):
+#     for j, q in enumerate(points):
+#         if i<=j: continue # Avoid duplicates
+#         # we'll work with square distances because it won't matter
+#         dist = math.dist(*[p,q])
+#         bisect.insort(distances, (dist, i, j), key=distance_key)
+
+distances = sorted(combinations(points,2), key=lambda p: math.dist(*p))
+
+circuits = {frozenset([p]) for p in points}
+
+def solution(distances, circuits, pairs=1000, part2=False):
+    for i, (p1, p2) in enumerate(distances):
+        if not part2 and i >= pairs:
+            circuits_by_len = sorted(circuits, key=len, reverse=True)
+            return math.prod([len(circuit) for circuit in circuits_by_len[:3]])
+        p1_group = [circuit for circuit in circuits if p1 in circuit][0]
+        p2_group = [circuit for circuit in circuits if p2 in circuit][0]
+        circuits -= {p1_group, p2_group}
+        circuits.add(p1_group | p2_group)
+        if part2 and len(circuits) == 1:
+            return p1[0] * p2[0]
+    return None # Impossible!
+
+
+# print(solution(distances, circuits, points, pairs=10))
+print(solution(distances, circuits))
+print(solution(distances, circuits, part2=True))