My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add 2025/08
+38
+38
2025/day08.py
+38
2025/day08.py
···
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import fileinput
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from collections import Counter
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from utils import UnionFind
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# Read problem input.
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BOXES = []
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for line in fileinput.input():
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a, b, c = [int(x) for x in line.split(',')]
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BOXES.append((a, b, c))
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# Precompute pairwise distances and sort ascending.
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DISTS = []
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for y, (a1, b1, c1) in enumerate(BOXES):
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for x, (a2, b2, c2) in enumerate(BOXES):
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if x >= y:
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continue
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dist = (abs(a2 - a1) ** 2) + (abs(b2 - b1) ** 2) + (abs(c2 - c1) ** 2)
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DISTS.append((dist, x, y))
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DISTS.sort()
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# Solve problem.
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TARGET_MERGES = 1000
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uf = UnionFind(len(BOXES))
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last_merge = None
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for it, (dist, x, y) in enumerate(DISTS):
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if not uf.in_same_set(x, y):
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uf.merge(x, y)
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last_merge = (BOXES[x], BOXES[y])
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if it == TARGET_MERGES - 1:
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circuits = [uf.find(i) for i in range(len(BOXES))]
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sizes = [size for circuit, size in Counter(circuits).most_common()]
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print("Part 1:", sizes[0] * sizes[1] * sizes[2])
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print("Part 2:", last_merge[0][0] * last_merge[1][0])