programming-examples/c/Search_Sorting/C Program to Permute All Letters of an Input String.c

#include <stdio.h>
#include <string.h>
void swap (char *x, char *y)
{
    char temp;
    temp = *x;
    *x = *y;
    *y = temp;
}

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
                }
        }
}

int main()
{
    char str[21];
    int len;
    printf("\nEnter a string: ");
    scanf("%s", str);
    len = strlen(str);
    permute(str, 0, len - 1);
    return 0;
}