Permutation of string

Backtracking Time Complexity: O(n*n!) # include <stdio.h>   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); //Base case    else    {         for (j = i; j <= n; j++) //Recursion case        {           swap((a+i), (a+j));           permute(a, i+1, n);           swap((a+i), (a+j)); //Backtrack!!!        }    } }   int main() {    char a[] = "ABC";     permute(a, 0, 2);    getchar();    return 0; }

Output:

ABC
ACB
BAC
BCA
CBA
CAB