38 lines
608 B
Crystal
38 lines
608 B
Crystal
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require "advent"
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INPUT = input(2020, 15).split(",").map(&.to_i32)
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def run(input, times)
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ls = {} of Int32 => {Int32,Int32}
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last = 0
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input.each_with_index do |n, i|
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ls[n] ||= {-1,-1}
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f,s = ls[n]
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ls[n] = {i,f}
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last = n
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end
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count = input.size
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while count < times
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n = 0
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if ls[last][1] != -1
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n = ls[last][0] - ls[last][1]
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end
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last = n
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ls[n] ||= {-1,-1}
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f,s = ls[n]
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ls[n] = {count,f}
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count += 1
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end
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last
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end
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def part1(input)
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run(input, 2020)
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end
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def part2(input)
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run(input, 30000000)
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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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