combinatorics.h

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/*
 * combinatorics.h
 *
 * LICENSE HERE
 *
 *  Created on: 2016-08-29
 *      Author: Rick Valenzano
 */
#ifndef COMBINATORICS_H_
#define COMBINATORICS_H_

#include <vector>
#include <stdlib.h>
#include <cstdint>
#include <string>

bool get_next_combo(std::vector<unsigned> &combo, unsigned k, unsigned n, bool first_combo = false);

template<class T>
void randomly_reorder(std::vector<T> &vec);

void get_rand_permutation(std::vector<unsigned> &perm, unsigned size);

uint64_t get_64_bit_factorial(unsigned n);

uint64_t get64BitnUpperk(unsigned n, unsigned k);

bool read_in_permutations(std::string file_name, std::vector<std::vector<unsigned> > &perms);

// Templated function implementations
template<class T>
void randomly_reorder(std::vector<T>& vec)
{
    unsigned pos = vec.size() - 1;
    // construct new permutation
    while(pos > 0) {
        int r = random();
        int index = r % (pos + 1);

        T temp = vec[index];
        vec[index] = vec[pos];
        vec[pos] = temp;

        pos--;
    }
}

#endif /* COMBINATORICS_H_ */