AdventOfCode2025/Day8.py

from functools import reduce
from heapq import heappush
from itertools import combinations

Box = tuple[int, int, int]

def distance_squared(left_box: Box, right_box: Box) -> int:
    return (right_box[0] - left_box[0])**2 + (right_box[1] - left_box[1])**2 + (right_box[2] - left_box[2])**2

def main():
    junction_boxes: list[Box]
    with open("input_day8.txt") as f:
        junction_boxes = [tuple(map(int, line.split(","))) for line in f]

    n = 10
    if len(junction_boxes) > 100:
        n = 1000

    distances: list[tuple[int, Box, Box]] = []

    for (left_box, right_box) in combinations(junction_boxes, 2):
        heappush(distances, (distance_squared(left_box, right_box), left_box, right_box))

    circuits: dict[int, list[Box]] = {i: [b] for i, b in enumerate(junction_boxes)}
    connected_junction_boxes: dict[Box, int] = {b: i for i, b in enumerate(junction_boxes)}

    for i, (_, left_box, right_box) in enumerate(sorted(distances)):
        if i == n:
            print(reduce(lambda x, y: x * y, sorted(map(len, circuits.values()), reverse=True)[:3]))


        left_circuit_id = connected_junction_boxes.get(left_box)
        right_circuit_id = connected_junction_boxes.get(right_box)
        if left_circuit_id != right_circuit_id:
            for box in circuits[right_circuit_id]:
                connected_junction_boxes[box] = left_circuit_id
            circuits[left_circuit_id].extend(circuits[right_circuit_id])
            del circuits[right_circuit_id]


        if len(circuits) == 1:
            print(left_box[0] * right_box[0])
            return



if __name__ == "__main__":
    main()