My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add solution for 2023/11
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2023/day11.py
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2023/day11.py
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import fileinput
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from itertools import combinations
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# Parse problem input.
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GALAXIES = set()
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for y, line in enumerate(fileinput.input()):
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for x, c in enumerate(line.strip()):
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if c == '#':
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GALAXIES.add((x, y))
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# Find "expanded" rows and columns.
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empty_row = set(range(y))
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empty_col = set(range(x))
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for (gx, gy) in GALAXIES:
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empty_col.discard(gx)
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empty_row.discard(gy)
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# Solve problem.
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part_1 = 0
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part_2 = 0
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for (sx, sy), (ex, ey) in combinations(GALAXIES, 2):
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crossed = 0
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for y in range(min(sy, ey), max(sy, ey) + 1):
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if y in empty_row:
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crossed += 1
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for x in range(min(sx, ex), max(sx, ex) + 1):
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if x in empty_col:
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crossed += 1
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# Raw distance is the Manhattan distance between the pair.
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raw_distance = abs(sy - ey) + abs(sx - ex)
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part_1 += raw_distance + crossed * 1
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part_2 += raw_distance + crossed * 999999
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print("Part 1:", part_1)
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print("Part 2:", part_2)
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