Question

Write a RECURSIVE method that receives 2 strings as parameters. The method will return true if the 2nd string is a subsequence of the 1st string. If not, the method will return false.

An empty string is a subsequence of every string. This is because all zero characters of the empty string will appear in the same relative order in any string

This method must not contain any loops.

In java

Answer 1

import java.io.*;

class SubSequence
{
   static boolean isSubSequence(String str1, String str2, int m, int n)
   {
       if (m == 0)
           return true;
       if (n == 0)
           return false;
          
       if (str1.charAt(m-1) == str2.charAt(n-1))
           return isSubSequence(str1, str2, m-1, n-1);
       return isSubSequence(str1, str2, m, n-1);
   }
  
   public static void main (String[] args)
   {
       String str1 = " "; //ENTER YOUR STRINGS BETWEEN THE DOUBLE INVERTED COMMA
       String str2 = " ";
       int m = str1.length();
       int n = str2.length();
       boolean res = isSubSequence(str1, str2, m, n);
       if(res)
           System.out.println("TRUE");
       else
           System.out.println("FALSE");
   }
}