Math code snippet to stripe away equal terms in two sets. For example: for sets n and d, where n = {1,2,3,4} and d = {1,2,3}, StripeAwayTerms replaces the 2 and 3 of both sets by a 1. This can be used to divide two factorials.


#include <vector>



//From http://www.richelbilderbeek.nl/CppStripeAwayTerms.htm

void StripeAwayTerms(std::vector<int>& v_x, std::vector<int>& v_y)

{

  std::vector<int>::iterator x = v_x.begin();

  const std::vector<int>::iterator x_end = v_x.end();

  for ( ; x!=x_end; ++x)

  {

    if (*x == 1) continue;

    std::vector<int>::iterator y = v_y.begin();

    const std::vector<int>::iterator y_end = v_y.end();

    for ( ; y!=y_end; ++y)

    {

      if (*y == 1) continue;

      if (*x % *y == 0) { *x/=*y; *y=1; }

      if (*y % *x == 0) { *y/=*x; *x=1; }

    }

  }

}

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(C++) StripeAwayTerms