38 lines
636 B
Crystal
38 lines
636 B
Crystal
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require "advent"
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INPUT = input(2020, 9).lines.map(&.to_i64)
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def is_sum(is, from, to, n)
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if to <= from
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return n == 0_i64
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end
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return is_sum(is, from, to-1, n) || is_sum(is, from, to-1, n-is[to-1])
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end
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def part1(input)
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is = input
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i = 25
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loop do
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return is[i] unless is_sum(is, i-25, i, is[i])
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i += 1
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end
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end
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def part2(input, i)
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input.each_with_index do |e, j|
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next if e == i
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acc = i-e
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k = j
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while acc > 0
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k += 1
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acc -= input[k]
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end
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if acc == 0
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min, max = input[j..k].minmax
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return min+max
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end
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end
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end
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p1 = part1(INPUT.clone)
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puts part2(INPUT.clone, p1)
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