61 lines
1.1 KiB
Python
61 lines
1.1 KiB
Python
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from re import finditer
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from collections import defaultdict
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from math import prod
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with open("input.txt") as f:
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lines = f.read().split("\n")
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### part 1
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symbols = {
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(i,j)
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for i, line in enumerate(lines)
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for j, c in enumerate(line)
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if c not in "1234567890."
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}
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part_numbers = []
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for i, line in enumerate(lines):
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for match in finditer(r"\d+", line):
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j1, j2 = match.span()
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number = int(match[0])
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window = {
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(i+x, j+y)
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for x in (-1, 0, 1)
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for y in (-1, 0, 1)
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for j in range(j1, j2)
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}
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for _ in window & symbols:
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part_numbers.append(number)
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part1 = sum(part_numbers)
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print(part1)
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### part 2
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potential_gears = {
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(i,j)
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for i, line in enumerate(lines)
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for j, c in enumerate(line)
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if c == "*"
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}
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parts = defaultdict(list)
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for i, line in enumerate(lines):
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for match in finditer(r"\d+", line):
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j1, j2 = match.span()
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number = int(match[0])
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window = {
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(i+x, j+y)
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for x in (-1, 0, 1)
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for y in (-1, 0, 1)
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for j in range(j1, j2)
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}
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for cell in window & potential_gears:
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parts[cell].append(number)
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gear_ratios = (prod(p) for p in parts.values() if len(p) == 2)
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part2 = sum(gear_ratios)
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print(part2)
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