Get Subsequence

 

package pep.Day9;

import java.util.ArrayList;

public class GetSubsequence {
    public static void main(String[] args) {
        String str = "abc";
        System.out.println(getSubsequence(str));
    }

    private static ArrayList<String> getSubsequence(String str) {
        if (str.length() == 0) {
            ArrayList<String> arr = new ArrayList<>();
            arr.add("");
            return arr;
        }
        char ch = str.charAt(0);
        String remString = str.substring(1);
        // base case
        ArrayList<String> faith = getSubsequence(remString);
        ArrayList<String> ans = new ArrayList();

        for (String f : faith) {
            ans.add(ch + f);
            ans.add("" + f);
        }
        return ans;
    }
}