Question

– Palindrome Game

Please write a Java program to verify whether a given word is a palindrome. You must stop your program when the user enters ‘@’ character as the word.

You may write a recursive program to solve this game, but you don’t have to.

You may use a stack and/or a queue to solve this game, but you don’t have to.

You must run 3 test cases for your program.   Your test case #1 must look as follows:

Welcome to the Palindrome World of Dr. Simon Lin!

Please enter a word (@ to quit) > racecar

The word racecar is a palindrome.

Please enter a word (@ to quit) > racersrecar

The word racersrecar is a palindrome.

Please enter a word (@ to quit) > racescar

The word racesar is NOT a palindrome.

Please enter a word (@ to quit) > mom

The word mom is a palindrome.

Please enter a word (@ to quit) > teacescaet

The word teacescaet is NOT a palindrome.

Please enter a word (@ to quit) > q

The word q is a palindrome.

Please enter a word (@ to quit) > @

Thank you for playing this Palindrome game designed by Dr. Simon Lin!

Answer 1

import java.util.Scanner;

public class PlaindromeRecursion {
   public static void main(String[] args) {
       Scanner sc = new Scanner(System.in);
       System.out.println("Please enter a word (@ to quit) ");
       String word = sc.nextLine();
       while (!word.equals("@")) {
           if (isPalRec(word, 0, word.length() - 1)) {
               System.out.println("The word " + word + " is a palindrome.");
           } else {
               System.out.println("The word " + word + " is a NOT a palindrome.");
           }
           System.out.println("Please enter a word (@ to quit) ");
           word = sc.nextLine();

       }
       System.out.println("Thank you for playing this Palindrome game designed by Dr. Simon Lin!");
   }

   static boolean isPalRec(String str, int s, int e) {
       // If there is only one character
       if (s == e)
           return true;

       // If first and last
       // characters do not match
       if ((str.charAt(s)) != (str.charAt(e)))
           return false;

       if (s < e + 1)
           return isPalRec(str, s + 1, e - 1);

       return true;
   }
}