DistinctPermutationsOfString

import java.util.HashSet;
import java.util.Set;

public class StringPermutationExample {
 
    public static void main(String[] args) {
        String input = "hlllo";
        String input2 = "where";
 
        Set<String> set = new HashSet<>();
 
        permutation(input, "", set);
        System.out.println(set);
        set.clear();
 
        permutation(input2, "", set);
        System.out.println(set);
    }
 
    private static void permutation(String input, String sofar, Set<String> set) {
        if (input.equals("")) {         //this becomes true when input.length becomes 0
            set.add(sofar);             // and so it is added to the set
        }
        int j =0;
        for (int i = 0; i < input.length(); i++) {
            char c = input.charAt(i);
            if (input.indexOf(c, i + 1) != -1)
                continue;       //this i+1 helps in getting index -1 when the input.length completes
            permutation(input.substring(0, i) + input.substring(i + 1), sofar + c, set);
        }
    }
 
}