Get Subsequence

 1. You are given a string str.

2. Complete the body of getSS function - without changing signature - to calculate all subsequences of str.
Use sample input and output to take idea about subsequences.

Input Format

A string str

Output Format

Contents of the arraylist containing subsequences as shown in sample output

Constraints
0 <= str.length <= 20
Sample Input
abc
Sample Output
[, c, b, bc, a, ac, ab, abc]

Solution:

import java.io.*;

import java.util.*;

public class Main {

    public static void main(String[] args) throws Exception {

        Scanner sc = new Scanner(System.in);

        String str = sc.nextLine();

        ArrayList<String> res = new ArrayList<>();

        res = gss(str);

        System.out.println(res);

    }

    public static ArrayList<String> gss(String str) {

        ArrayList<String> res = new ArrayList<>();

        if(str.length() == 0){

            res.add("");

            return res;

        }

        

        String ch = str.substring(0,1);

        String subStr = str.substring(1);

        ArrayList<String> it_res = gss(subStr);

        

        for(String s:it_res)

            res.add(s);

        

        for(String s:it_res)

            res.add(ch+s);

            

        return res;

    }

}