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 CBA CAB

Recommended: Please solve it on “PRACTICE ” first, before moving on to the solution.

C/C++

filter_none

edit
close

play_arrow

link
brightness_4
code

// C program to print all permutations with duplicates allowed
#include <stdio.h>
#include <string.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 l, int r)
{
    int i;
    if (l == r)
        printf("%s\n", a);
    else {
        for (i = l; i <= r; i++) {
            swap((a + l), (a + i));
            permute(a, l + 1, r);
            swap((a + l), (a + i)); // backtrack
        }
    }
}
  
/* Driver program to test above functions */
int main()
{
    char str[] = "ABC";
    int n = strlen(str);
    permute(str, 0, n - 1);
    return 0;
}

chevron_right


Output:



ABC
ACB
BAC
BCA
CBA
CAB

Please refer complete article on Write a program to print all permutations of a given string for more details!



My Personal Notes arrow_drop_up


Article Tags :

1


Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.