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63 lines
1.4 KiB
63 lines
1.4 KiB
6 days ago
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tiles = DATA.readlines(chomp: true).flat_map.with_index {|row, y|
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row.chars.filter_map.with_index {|tile, x|
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tile == ?# ? nil : [[y,x], tile]
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}
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}.to_h
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start, stop = %w[ S E ].map {|t| tiles.find { _2 == t }[0] }
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scores = Hash.new(Float::INFINITY)
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scores[[start, [0,1]]] = 0
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queue = [[start, [0,1]]]
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visited = Set.new
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loop do
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fail if queue.empty?
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current, dir = queue.shift
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visited << [current, dir]
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score = scores.fetch([current, dir])
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break if current == stop
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# straight ahead
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yx = current.zip(dir).map { _1 + _2 }
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if tiles.has_key?(yx)
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scores[[yx, dir]] = [scores[[yx, dir]], score + 1].min
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queue << [yx, dir] unless visited.include?([yx, dir])
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end
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# sides
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[-1, 1].each do |d|
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delta = dir.reverse.zip([d, d]).map { _1 * _2 }
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yx = current.zip(delta).map { _1 + _2 }
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if tiles.has_key?(yx)
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scores[[yx, delta]] = [scores[[yx, delta]], score + 1001].min
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queue << [yx, delta] unless visited.include?([yx, delta])
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end
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end
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queue.uniq!
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queue.sort_by! { scores.fetch(_1) }
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end
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pp scores.find {|(yx,_),_| yx == stop }[1]
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__END__
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#################
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#...#...#...#..E#
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#.#.#.#.#.#.#.#^#
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#.#.#.#...#...#^#
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#.#.#.#.###.#.#^#
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#>>v#.#.#.....#^#
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#^#v#.#.#.#####^#
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#^#v..#.#.#>>>>^#
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#^#v#####.#^###.#
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#^#v#..>>>>^#...#
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#^#v###^#####.###
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#^#v#>>^#.....#.#
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#^#v#^#####.###.#
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#^#v#^........#.#
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#^#v#^#########.#
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#S#>>^..........#
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#################
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