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43 lines
762 B
43 lines
762 B
input = DATA.readlines(chomp: true)
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.flat_map.with_index {|row, y|
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row.chars.map.with_index {|chr, x|
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[[y,x], chr]
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}
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}.to_h
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# part one
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dirs = (-1..1).flat_map {|dy| (-1..1).map {|dx| [dy,dx] }}
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dirs.delete([0,0])
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dirs = dirs.map {|dy, dx|
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4.times.map {|i| [dy*i, dx*i] }
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}
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pp input.keys.sum {|y, x|
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dirs.count {|deltas|
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deltas.map {|dy, dx| input[[y+dy, x+dx]] }.join == "XMAS"
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}
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}
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# part two
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diagonals = [
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[[-1, 1], [1, -1]],
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[[-1, -1], [1, 1]],
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]
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pp input.keys.select {|y, x|
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input[[y,x]] == ?A && diagonals.all? {|deltas|
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deltas.map {|dy,dx| input[[y+dy, x+dx]] }.to_set == Set["M", "S"]
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}
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}.size
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__END__
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MMMSXXMASM
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MSAMXMSMSA
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AMXSXMAAMM
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MSAMASMSMX
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XMASAMXAMM
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XXAMMXXAMA
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SMSMSASXSS
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SAXAMASAAA
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MAMMMXMMMM
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MXMXAXMASX
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