AdventOfCode-2020/day12.cr

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