PrintUniqueSubsets.java

package RecursionAndBacktracking;
/*
* We have given a string, and we have to print the unique not repeated subsets of the given string.
* Example :
* String : "aab"
* Output : "", "a", "b", "aa", "ab", "aab"
*
*
* Hint : For this we simply store the result into Set in the base case.
*/
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class PrintUniqueSubsets {
 static Set<String> set = new HashSet<>();
 public static void printUniqueSubsets(String output, String input){
 // Base Case
 if(input.equals("")){
 if(output.equals("")){ // if the output string is empty then print " "
 set.add("\" \"");
 }else { // else print output string
 set.add("\"" + output + "\"");
 }
 return;
 }
 // divide the tree into two child left and right
 String outputLeft = output;
 String outputRight = output;

 // For left child : we take output string as it is before
 // For right child : we take output string by appending the 0th character of the input string
 outputRight += input.charAt(0);
 // Now update input string by deleting 0th character of the input string
 input = input.substring(1);
 // Now simply call the recursive function
 printUniqueSubsets(outputLeft, input);
 printUniqueSubsets(outputRight, input);
 }
 public static void main(String[] args) {
 Scanner sc = new Scanner(System.in);
 System.out.println("Enter the input string:");
 String input = sc.next();
 String output = "";
 printUniqueSubsets(output, input);
 System.out.println(set);
 }
}