8 lines
344 B
APL
8 lines
344 B
APL
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⍝ Builtin version, takes a vector:
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⎕CY'dfns'
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perms←{↓⍵[pmat ≢⍵]} ⍝ pmat always gives lexicographically ordered permutations.
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⍝ Recursive fast implementation, courtesy of dzaima from The APL Orchard:
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dpmat←{1=⍵:,⊂,0 ⋄ (⊃,/)¨(⍳⍵)⌽¨⊂(⊂(!⍵-1)⍴⍵-1),⍨∇⍵-1}
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perms2←{↓⍵[1+⍉↑dpmat ≢⍵]}
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