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81 lines
1.6 KiB
81 lines
1.6 KiB
garden = DATA.readlines(chomp: true).flat_map.with_index {|row, y|
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row.chars.map.with_index {|id, x| [[y,x], id] }
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}.to_h
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DELTAS = [[-1, 0], [1, 0], [0, -1], [0, 1]]
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queue = Set[*garden.keys]
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plots = [Set[queue.first]]
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until queue.empty?
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yx = plots.last.select { queue.include?(_1) }.first
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if yx.nil?
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plots << Set[queue.first] if queue.first
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next
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end
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queue.delete(yx)
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id = garden.fetch(yx)
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neighbors = DELTAS
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.map {|d| yx.zip(d).map { _1 + _2 }}
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.select { garden.fetch(_1, nil) == id }
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if neighbors.empty?
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plots << Set[queue.first] if queue.first
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else
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plots.last.merge(neighbors)
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end
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end
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perimeter = ->(plot) {
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plot.flat_map {|yx|
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DELTAS
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.map {|delta| yx.zip(delta).map { _1 + _2 }}
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.reject { garden.fetch(_1, nil) == garden[plot.first] }
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}
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}
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pp plots
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.map { [_1.size, perimeter[_1]] }
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.sum { _1 * _2.length }
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sides = ->(plot) {
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id = garden.fetch(plot.first)
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rows = plot.group_by(&:first).values.flat_map {|row|
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[-1, 1].flat_map {|dy|
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row
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.map {|y,x| [y+dy, x] }
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.reject { garden.fetch(_1, nil) == id }
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.map(&:last)
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.sort
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.chunk_while { _1 + 1 == _2 }
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}
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}
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cols = plot.group_by(&:last).values.flat_map {|row|
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[-1, 1].flat_map {|dx|
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row
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.map {|y,x| [y, x+dx] }
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.reject { garden.fetch(_1, nil) == id }
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.map(&:first)
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.sort
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.chunk_while { _1 + 1 == _2 }
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}
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}
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rows + cols
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}
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pp plots
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.map { [garden.fetch(_1.first), _1.size, sides[_1]] }
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.sum { _2 * _3.sum(&:count) }
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__END__
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