Question

in java

Write a class named Palindrome.java and Write a method isPalindrome that takes an IntQueue as a parameter and that returns whether or not the numbers in the queue represent a palindrome (true if they do, false otherwise). A sequence of numbers is considered a palindrome if it is the same in reverse order. For example, suppose a Queue called q stores this sequence of values:

front [3, 8, 17, 9, 17, 8, 3] back

Then the following call:

isPalindrome(q)

should return true because this sequence is the same in reverse order. If the list had instead stored these values:

front [3, 8, 17, 9, 4, 17, 8, 3] back

the call on isPalindrome would instead return false because this sequence is not the same in reverse order (the 9 and 4 in the middle don't match).

The empty queue should be considered a palindrome. You may not make any assumptions about how many elements are in the queue and your method must restore the queue so that it stores the same sequence of values after the call as it did before.

The method header is specified as follows:

public static boolean isPalindrome(IntQueue q)

To test your program, click to select the PalindromeTester.class and Run JUnit button Note: class name, variable name, and method names MUST be the same as specified.

Given files (for help)

IntQueue.txt

public class IntQueue{
Integer[] arr;
int numOfElements=0;
int front=0;
int rear=-1;

public IntQueue(int cap);

public void enqueue(Integer data);
public Integer dequeue();

public boolean isFull();

public boolean isEmpty();
}

IntStack.txt

methods document:

public class IntStack{
Integer[] arr;
int index=0;

public IntStack(int cap);

public void push(Integer data);
public Integer pop();
public Integer top();
public boolean isFull();

public boolean isEmpty();

}

Answer 1

Here is the completed code for this problem. Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. If you are satisfied with the solution, please rate the answer. Thanks

//Palindrome.java

public class Palindrome {

    /**

    * required method. Assuming IntQueue and IntStack classes are defined

    * correctly and within the same package.

    *

    * @param q

    *            input queue of integers

    * @return true if numbers in q constitute a palindrome, else false

    */

    public static boolean isPalindrome(IntQueue q) {

         // initially assuming q is palindromic

         boolean pal = true;

         // creating a stack and a queue of size 100, assuming input q size is

         // never more than 100 (this is needed because the constructors in the

         // stack and queue classes you provided take size as parameter; if you

         // are having any issues with testing, then increase the size as you

         // need)

         IntStack stk = new IntStack(100);

         IntQueue que = new IntQueue(100);

         // looping until q is empty

         while (!q.isEmpty()) {

             // topping front element from q

             Integer value = q.dequeue();

             // adding to both stk and que

             stk.push(value);

             que.enqueue(value);

         }

         // now looping until que is empty

         while (!que.isEmpty()) {

             // fetching front value from que and top value from stk

             Integer value1 = que.dequeue();

             Integer value2 = stk.pop();

             // if they mismatch, setting pal to false (not a palindrome)

             if (!value1.equals(value2)) {

                 pal = false;

             }

             // adding value1 to q, so that after the loop, contents of q will

             // remain the same.

             q.enqueue(value1);

         }

         return pal;

    }

}