65 lines
1.4 KiB
Crystal
65 lines
1.4 KiB
Crystal
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require "advent"
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INPUT = input(2020, 11).lines.map(&.chars)
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abstract class Search
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def search(current, x, y, dx, dy)
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x, y = x + dx, y + dy
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return 0 if y < 0 || y >= current.size
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return 0 if x < 0 || x >= current[y].size
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search_impl(current,x,y,dx,dy)
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end
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abstract def search_impl(current, x, y, dx, dy)
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end
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class FirstSearch < Search
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def search_impl(current, x, y, dx, dy)
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return current[y][x] == '#' ? 1 : 0
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end
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end
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class SecondSearch < Search
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def search_impl(current, x, y, dx, dy)
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return 1 if current[y][x] == '#'
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return 0 if current[y][x] == 'L'
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return search(current, x, y, dx, dy)
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end
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end
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DIRS = [{-1,-1}, {-1, 0}, {-1, 1}, {0, -1}, {0, 1}, {1, -1}, {1, 0}, {1,1}]
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def step(current, step, check, n)
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current.each_with_index do |row, y|
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row.each_with_index do |seat, x|
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step[y][x] = current[y][x]
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count = DIRS.sum do |dx, dy|
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check.search(current, x, y, dx, dy)
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end
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step[y][x] = 'L' if seat == '#' && count >= n
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step[y][x] = '#' if seat == 'L' && count == 0
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end
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end
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{step, current}
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end
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def run(input, search, n)
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current = input
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step = input.clone
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loop do
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current, step = step(current, step, search, n)
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break if current.zip_with(step) { |l, r| l == r }.all?
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end
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current.sum(&.count(&.==('#')))
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end
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def part1(input)
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run(input, FirstSearch.new, 4)
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end
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def part2(input)
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run(input, SecondSearch.new, 5)
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end
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puts part1(INPUT.clone)
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puts part2(INPUT.clone)
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