74 lines
1.7 KiB
Factor
74 lines
1.7 KiB
Factor
USING: kernel math sequences namespaces errors hashtables words
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arrays parser compiler syntax io optimizer inference shuffle
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tools prettyprint ;
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IN: random-tester
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: pick-one ( seq -- elt )
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[ length random-int ] keep nth ;
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! HASHTABLES
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: random-hash-entry ( hash -- key value )
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hash>alist pick-one first2 ;
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: coin-flip ( -- bool ) 2 random-int zero? ;
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: do-one ( seq -- ) pick-one call ; inline
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: nzero-array ( seq -- )
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dup length >r 0 r> [ pick set-nth ] each-with drop ;
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: zero-array
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[ drop 0 ] map ;
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TUPLE: p-list seq max count count-vec ;
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: make-p-list ( seq n -- tuple )
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>r dup length [ 1- ] keep r>
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[ ^ 0 swap 2array ] keep
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zero-array <p-list> ;
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: inc-seq ( seq max -- )
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2dup [ < ] curry find-last over -1 = [
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3drop nzero-array
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] [
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nipd 1+ 2over swap set-nth
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1+ over length rot <slice> nzero-array
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] if ;
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: inc-count ( tuple -- )
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[ p-list-count first2 >r 1+ r> 2array ] keep
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set-p-list-count ;
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: get-permutation ( tuple -- seq )
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[ p-list-seq ] keep p-list-count-vec [ swap nth ] map-with ;
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: p-list-next ( tuple -- seq/f )
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dup p-list-count first2 < [
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[
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[ get-permutation ] keep
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[ p-list-count-vec ] keep p-list-max
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inc-seq
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] keep inc-count
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] [
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drop f
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] if ;
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: (permutations) ( tuple -- )
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dup p-list-next [ , (permutations) ] [ drop ] if* ;
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: permutations ( seq n -- seq )
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make-p-list
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[
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(permutations)
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] { } make ;
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: (each-permutation) ( tuple quot -- )
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over p-list-next [
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[ rot drop swap call ] 3keep
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drop (each-permutation)
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] [
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2drop
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] if* ; inline
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: each-permutation ( seq n quot -- )
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>r make-p-list r> (each-permutation) ;
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