Permutation2

Interface

Class Permutation2

This class progressively generates all the permutations of the given size, while also giving the possibility to return the rank and parity of the current permutation.

Example:

#include <codecogs/maths/combinatorics/permutations/permutation2.h>
#include <iostream>
int main()
{
  Maths::Combinatorics::Permutations::Permutation2 P(3);
  std::cout << "The permutations of 3 elements:";
  std::cout << std::endl;
  for (int i = 0; i < 6; i++)
  {
    std::vector<int> alpha = P.getNext();
    for (int j = 0; j < alpha.size(); j++)
      std::cout << alpha[j] << " ";
    if (P.isEven())
      std::cout << "\tis even";
    else
      std::cout << "\tis odd";
    std::cout << "\t rank = " << P.getRank();
    std::cout << std::endl;
  }
  return 0;
}

Output:

The permutations of 3 elements:
1 2 3   is even  rank = 1
1 3 2   is odd   rank = 2
3 1 2   is even  rank = 3
3 2 1   is odd   rank = 4
2 3 1   is even  rank = 5
2 1 3   is odd   rank = 6

References:

SUBSET, a C++ library of combinatorial routines, http://www.csit.fsu.edu/~burkardt/cpp_src/subset/subset.html

Authors

Lucian Bentea (August 2005)

Source Code

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