#include <iostream.h>

void perm (char *a, const int k, const int n) {
// n is the size of a
// Generate all the permutations of a[k], ..., a[n-1].

if (k == n-1) {  // output permutation
   for (int i = 0; i < n; i++) 
      cout << a[i] << " ";
   cout << endl;
   }
else { 
// a[k], ..., a[n-1] has more than one permutation.Generate these recursively
   for (int i = k; i < n; i++) {
// interchange a[k] and a[i]
      char temp = a[k]; 
      a[k] = a[i]; 
      a[i] = temp;
      perm(a, k+1, n); // all permutations of a[k+1], ..., a[n-1]
// interchange a[k] and a[i] again, to return to the original configuration
      temp = a[k]; 
      a[k] = a[i]; 
      a[i] = temp;
      }
   } // end of else
} // end of perm
//----------------------------------------------------------------------------
void main()
{
   char b[10];
   b[0] = 'a'; b[1] = 'b'; b[2] = 'c'; b[3] = 'd'; b[4] = 'e';
   b[5] = 'f'; b[6] = 'g';

   perm(b,0,3);
   cout << endl;
}