permutationsstl.cpp

这是数据结构、算法与应用-C++语言描述的代码

// output all permutations of n elements using the STL function next_permutation
// elements must be in ascending order initially
// permutations generated in lexicographic order

#include <iostream>
#include <algorithm> // has copy & next_permutation

using namespace std;

template<class T>
void permutations(T list[], int k, int m)
{// Generate all permutations of list[k:m].
 // Assume k <= m.
   // output the permutations one by one
   do {
      copy(list, list+m+1,
            ostream_iterator<T>(cout, ""));
      cout << endl;
   } while (next_permutation(list, list+m+1));
}

int main()
{
   char a[] = {'1', '2', '3', '4'};

   cout << "The permutations of 1 are" << endl;
   permutations(a, 0, 0);

   cout << "The permutations of 123 are" << endl;
   permutations(a, 0, 2);

   cout << "The permutations of 1234 are" << endl;
   permutations(a, 0, 3);
   return 0;
}