Write out a function that prints out all the permutations of
a string.

For example, abc would give you abc, acb, bac, bca, cab,
cba. You can assume that all the characters will be unique.

Answer Posted / fallen angel

use plain recursion
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
void swap(char* src, char* dst)
{
char ch = *dst;
*dst = *src;
*src = ch;
}
/* permute [set[begin], set[end]) */
int permute(char* set, int begin, int end)
{
int i;
int range = end - begin;
if (range == 1) {
printf("set: %s\n", set);
} else {
for(i=0; i<range; i++) {
swap(&set[begin], &set[begin+i]);
permute(set, begin+1, end);
swap(&set[begin], &set[begin+i]);
/* set back */
}
}
return 0;
}
int main()
{
char str[] = "abcd";
permute(str, 0, strlen(str));
return 0;
}

Is This Answer Correct ?    28 Yes 9 No



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