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66 lines
1.3 KiB
66 lines
1.3 KiB
def succ(coord, delta)
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coord.zip(delta).map { _1 + _2 }
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end
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map = ARGF.readlines(chomp: true)
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.flat_map.with_index {|row, y|
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row.chars.map.with_index {|elem, x|
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[[y,x], elem.to_i]
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}
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}.to_h
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max_y = map.keys.map(&:first).max
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max_x = map.keys.map(&:last).max
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dest = [max_y,max_x]
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Node = Data.define(:pos, :dir, :continued)
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frontier = []
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visited = {}
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# seed initial directions
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[
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[1,0], # down
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[0,1], # right
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].each do |dir|
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node = Node.new(dir, dir, 1)
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frontier << node
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visited[node] = map.fetch(dir)
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end
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loop do
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frontier.sort_by! { visited.fetch(_1) }
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current = frontier.shift
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nexts = []
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# turn left and right
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if current.continued > 3
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nexts.concat([current.dir.reverse, current.dir.reverse.map { -_1 }].map {|turn|
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Node.new(current.pos.zip(turn).map { _1 + _2 }, turn, 1)
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})
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end
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# keep going?
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if current.continued < 10
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nexts << Node.new(
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current.pos.zip(current.dir).map { _1 + _2 },
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current.dir,
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current.continued + 1,
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)
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end
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if found = nexts.find { _1.pos == dest && (4..10).cover?(_1.continued) }
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p visited.fetch(current) + map.fetch(dest)
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exit
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end
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nexts
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.select { map.has_key?(_1.pos) }
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.reject { visited.has_key?(_1) }
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.each do |node|
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frontier << node
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visited[node] = visited.fetch(current) + map.fetch(node.pos)
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end
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end
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