Permutations of a Given String

Problem Statement

Pattern:

---

Solution

ArrayList<String> res;
 
public void swap (char[] chars, int a, int b ) {
	char temp = chars[a];
	chars[a] = chars[b];
	chars[b] = temp;
}
 
public void p (char[] chars, int start) {
	if(start == chars.length-1) {
		res.add(new String(chars));
		return;
	}
		
	for(int i = start; i < chars.length; i++) {
		swap(chars, i, start);
		p(chars, start + 1);
		swap(chars, i, start);
	}
}
 
public List<String> find_permutation(String S) {
	// Code here
	res = new ArrayList<String>();
	p(S.toCharArray(), 0);
	return res;
}

TC : $n\ast n!$ SC :

Notes