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39 lines
843 B
39 lines
843 B
require "set"
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cavern = ARGF.read.split("\n").map { _1.chars.map(&:to_i) }
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cavern = (0..4).flat_map {|i| cavern.map {|row|
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row.map { (_1 + i - 1) % 9 + 1 }
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}}
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cavern = cavern.map {|row| (0..4).flat_map {|i|
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row.map { (_1 + i - 1) % 9 + 1 }
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}}
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cavern = cavern
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.flat_map.with_index {|row,y| row.map.with_index {|risk,x| [[y,x], risk] }}
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.to_h
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bottom_right = cavern.keys.max
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risks = Hash.new(0)
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risks[[0,0]] = 0
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edges = Set[[0,0]]
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until risks.has_key?(bottom_right)
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yx = edges.min_by { risks.fetch(_1) }
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edges.delete(yx)
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y,x = yx
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neighbors = [[-1, 0], [1, 0], [0, 1], [0, -1]]
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.map {|dy,dx| [y+dy, x+dx] }
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.select { cavern.has_key?(_1) }
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.reject { risks.has_key?(_1) }
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risk = risks.fetch(yx)
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neighbors.each do
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risks[_1] = risk + cavern.fetch(_1)
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end
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edges.merge(neighbors)
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end
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p risks[bottom_right]
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