permuation.c

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

void swap(char* a, int left, int right) {
	char t = a[left];
	a[left] = a[right];
	a[right] = t;
}

void permuation(char* a, int left, int right) {
	if (right == left) {
		printf("%s\n", a);
	} else {
		for (int i = left; i < right; i++) {
			swap(a, left, i);
			permuation(a, left + 1, right);
			swap(a, left, i);
		}
	}
}

int main() {
	char a[] = "abc";
	permuation(a, 0, strlen(a));
}