Write a C program to print all permutations of a given string

A permutation, also called an “arrangement number” or “order,” is a rearrangement of the elements of an ordered list S into a one-to-one correspondence with S itself. A string of length n has n! permutation.
Source: Mathword(http://mathworld.wolfram.com/Permutation.html)
Below are the permutations of string ABC.
ABC, ACB, BAC, BCA, CAB, CBA
Here is a solution using backtracking.

# include <stdio.h>

 

/* Function to swap values at two pointers */

void swap (char *x, char *y)

{

    char temp;

    temp = *x;

    *x = *y;

    *y = temp;

}

  

/* Function to print permutations of string

   This function takes three parameters:

   1. String

   2. Starting index of the string

   3. Ending index of the string. */

void permute(char *a, int i, int n)

{

   int j;

   if (i == n)

     printf("%s\n", a);

   else

   {

        for (j = i; j <= n; j++)

       {

          swap((a+i), (a+j));

          permute(a, i+1, n);

          swap((a+i), (a+j)); //backtrack

       }

   }

}

 

/* Driver program to test above functions */

int main()

{

   char a[] = "ABC"; 

   permute(a, 0, 2);

   getchar();

   return 0;

}

 

 

Output:

ABC
ACB
BAC
BCA
CBA
CAB

Algorithm Paradigm: Backtracking
Time Complexity: O(n*n!)
Please write comments if you find the above codes/algorithms incorrect, or find other ways to solve the same problem.