Re^5: Derangements iterator


go ahead... be a heretic
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Re^5: Derangements iterator

by Jedaī (Initiate)

on Dec 31, 2005 at 13:34 UTC ( [id://520145]=note: print w/replies, xml )

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in reply to Re^4: Derangements iterator
in thread Derangements iterator

Oops.. Sorry, the wrapper performs unnecessary operations, here a good version :

use Inline C => <<'END_OF_C_CODE';

void cderange ( SV* truc, ... ){
  SV* sv_temp;
  I32 index, i;
  Inline_Stack_Vars;

  srand(time( NULL ));
  index = Inline_Stack_Items;
  for (; index; index--) {
    i = (I32) (rand() % (index));
    sv_temp = Inline_Stack_Item(index);
    Inline_Stack_Item(index) = Inline_Stack_Item(i);
    Inline_Stack_Item(i) = sv_temp;
  }
  Inline_Stack_Done;
}

END_OF_C_CODE
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Very fast, but this code is subject to the same caveat as Algorithm::Numerical::Shuffle.