63 lines
1.1 KiB
Crystal
63 lines
1.1 KiB
Crystal
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require "advent"
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INPUT = input(2020, 12).lines.map do |l|
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{l[0], l[1..].to_i32}
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end
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def part1(input)
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pos = {0, 0}
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angle = 0
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input.each do |c, n|
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case c
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when 'N'
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pos = pos.add({0, n})
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when 'S'
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pos = pos.add({0, -n})
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when 'E'
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pos = pos.add({n, 0})
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when 'W'
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pos = pos.add({-n, 0})
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when 'L'
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angle = (angle + n) % 360
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when 'R'
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angle = (angle + (360-n)) % 360
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when 'F'
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dists = [{1, 0}, {0, 1}, {-1, 0}, {0, -1}]
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dx, dy = dists[angle//90]
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pos = pos.add({dx * n, dy * n})
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end
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end
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pos.map(&.abs).sum
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end
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def part2(input)
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pos = {10, 1}
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spos = {0, 0}
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angle = 0
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input.each do |c, n|
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case c
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when 'N'
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pos = pos.add({0, n})
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when 'S'
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pos = pos.add({0, -n})
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when 'E'
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pos = pos.add({n, 0})
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when 'W'
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pos = pos.add({-n, 0})
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when 'L'
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(n//90).times do
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pos = {-pos[1], pos[0]}
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end
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when 'R'
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(n//90).times do
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pos = {pos[1], -pos[0]}
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end
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when 'F'
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spos = spos.add({pos[0] * n, pos[1]*n})
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end
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end
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spos.map(&.abs).sum
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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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