56 lines
958 B
Crystal
56 lines
958 B
Crystal
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INPUT = File.read("day5.txt").lines.map(&.chomp)
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def partition(choices, list)
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b = 0
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e = list.size
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choices.chars.each do |c|
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b = (b+e)//2 if c == 'B' || c == 'R'
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e = (b+e)//2 if c == 'F' || c == 'L'
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end
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return {b,e}
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end
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def get_id(str)
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col = str[0..6]
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row = str[7..]
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{partition(col, (0..127).to_a)[0], partition(row, (0..7).to_a)[0]}
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end
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def id(t)
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r, c = t
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r * 8 + c
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end
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def part1
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input = INPUT.clone
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max = input.max_of do |line|
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r, c = get_id(line)
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r * 8 + c
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end
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puts max
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end
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def part2
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input = INPUT.clone
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seen = Set(Int32).new
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max = input.each do |line|
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seen << id(get_id(line))
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end
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candidates = [] of Int32
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128.times do |r|
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next if r == 0 || r == 127
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8.times do |c|
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next if seen.includes? id({r, c})
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candidates << id({r,c})
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end
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end
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candidates = candidates.select do |i|
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seen.includes?(i-1) && seen.includes?(i+1)
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end
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puts candidates[0]
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end
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part1
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part2
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