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71 lines
2.3 KiB
71 lines
2.3 KiB
input = ARGF.readlines(chomp: true).map {|row|
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springs, groups = row.split(" ")
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[springs, groups.scan(/\d+/).map(&:to_i)]
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}
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p input
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# .map { [ _1.chars, _2 ] }
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.map { [Array.new(5, _1).join(??).chars, _2 * 5] }
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.map {|springs, groups|
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arrangement_counts = Hash.new {|h,k|
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count, springs, groups = k
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first, *rest = springs
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h[k] = case [count, first, groups]
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in count, _, []
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if count.nonzero?
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0
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elsif springs.include?(?#)
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0
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else
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1
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end
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in count, _, groups if count > groups.fetch(0)
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0 # early exit if the damaged group ever gets too large
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in count, nil, groups # no more springs
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if groups.size > 1
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0
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elsif count == groups.fetch(0)
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1
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else
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0
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end
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in count, ?#, groups # continue a damaged group
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h[[count + 1, rest, groups]]
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in 0, ?., groups
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h[[0, rest, groups]]
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in count, ?., groups # finish a damaged group
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if count == groups.fetch(0)
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h[[0, rest, groups[1..]]]
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else
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0
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end
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in count, ??, g if count == g.fetch(0) # unknown spring, matched current group
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h[[0, rest, g[1..]]]
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in count, ??, g unless count.zero? # unknown spring, ongoing group
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h[[count + 1, rest, g]]
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in count, ??, g # unknown spring
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[
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h[[count, rest, g]], # undamaged
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h[[count + 1, rest, g]], # damaged
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].sum
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else
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fail "#{{first:, springs: springs.join, groups:}}"
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end
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}
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arrangement_counts[[0, springs, groups]]
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}.sum
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# original part one
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# p input.map {|springs, groups|
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# unknowns = springs.count(??)
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# (0...2**unknowns).map {|arrangement|
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# arrangement = arrangement.to_s(2).rjust(unknowns, ?0).chars.map { _1 == ?0 ? ?. : ?# }
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# candidate = springs.gsub(??) { arrangement.shift }
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# candidate.chars
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# .slice_when { _1 != _2 }
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# .reject { _1[0] == ?. }
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# .map(&:size) == groups
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# }.count(&:itself)
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# }.sum
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