Question

How to write a recursive function to generate all permutations of a string in C

Answer 1

#include <stdio.h>
#include <string.h>

// Swap two characters
void swap(char *x, char *y) {
    char temp = *x;
    *x = *y;
    *y = temp;
}

// Recursive function to generate permutations
void generatePermutation(char *str, int l, int r) {
    if (l == r) {
        printf("%s\n", str);
    } else {
        for (int i = l; i <= r; i++) {
            swap(&str[l], &str[i]);
            generatePermutation(str, l + 1, r);
            swap(&str[l], &str[i]); // backtrack
        }
    }
}

int main() {
    char s[] = "ABC";

    generatePermutation(s, 0, strlen(s) - 1);
}


  
 
/* 
run:
 
ABC
ACB
BAC
BCA
CBA
CAB
 
*/

 

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