23 lines
677 B
Julia
23 lines
677 B
Julia
function johnsontrotter(low, high)
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function permutelevel(vec)
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if length(vec) < 2
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return [vec]
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end
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sequences = []
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endint = vec[end]
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smallersequences = permutelevel(vec[1:end-1])
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leftward = true
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for seq in smallersequences
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for pos in (leftward ? (length(seq)+1:-1:1): (1:length(seq)+1))
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push!(sequences, insert!(copy(seq), pos, endint))
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end
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leftward = !leftward
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end
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sequences
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end
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permutelevel(collect(low:high))
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end
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for (i, sequence) in enumerate(johnsontrotter(1,4))
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println("""$sequence, $(i & 1 == 1 ? "+1" : "-1")""")
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end
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