Question

Comeputer science .This is java problem.

PROBLEM 1

Queue (Links to an external site.) is an abstract data type (ADT) consisting of a sequence of entities with a first-in-first-out (FIFO) (Links to an external site.) property. Queue has the following operations, in alignment with the Java Queue interface (Links to an external site.) in the Oracle's SDK:

• add(x): inserts the specified x element to the back of queue without violating capacity limitation.
• remove(): removes the head (front) of queue, returning the removed element.
• peek(): retrieves and displays but does not remove (i.e., read-only) the head of queue.
• isEmpty: returns whether the queue is empty or not as boolean.

Implement the above FOUR (4) operations in your Solution class as follows. You are responsible for implementing the area shown in red below. Note that you are given TWO (2) local Stacks to help you manage the above listed queue operations.

STARTER CODE

import java.util.Stack;
public class HomeworkAssignment5_1 {    
    public static void main(String[] args) {
       // just like any problems, whatever you need here, etc.
    }
}
class Solution {

   // YOUR STACK TO USE FOR THIS PROBLEM
   private Stack<Integer> pushStack = new Stack<Integer>();
   private Stack<Integer> popStack = new Stack<Integer>();

   /* =====================================
   /* !!! DO NOT MODIFY ABOVE THIS LINE!!!
   /* ====================================

   // YOUR STYLING DOCUMENTATION HERE
   public void add(int x) { 
      // YOUR CODE HERE
   }
   // YOUR STYLING DOCUMENTATION HERE
   public int remove() { 
      // YOUR CODE HERE
   }
   // YOUR STYLING DOCUMENTATION HERE
   public int peek() { 
      // YOUR CODE HERE
   }
   // YOUR STYLING DOCUMENTATION HERE
   public boolean isEmpty() { 
     // YOUR CODE HERE
   }
}

EXAMPLES

// TEST CASE #1
Solution sol = new Solution();
sol.add(8);
sol.add(1);  
sol.peek();     // 8 (if you use System.out.println(), for example)
sol.remove();   // 8
sol.isEmpty();  // false
sol.remove();   // 1
sol.isEmpty();  // true
sol.add(2);     
sol.add(3); 
sol.peek();     // 2

// TEST CASE #2
// etc.

CONSTRAINTS / ASSUMPTIONS

• You must use Java Stack (Links to an external site.) (java.utils.Stack), both local pushStack and popStack instances, to implement the solution queue for this problem; failure to do so receives 0 logic points.
• You must use only the standard Stack methods, pop(), push(), peek(), and empty(), for this problem.
• This problem tests your understanding of how queue works in Java by implementing it from scratch using the Stack ADT you learned.
• All operations called on the queue are valid. In other words, both remove() and peek() will NOT be called on an empty queue. This means you won't have to create any Exceptions to handle errors.
• Your solution will be tested against 9-10 test cases; -1 for each failed test.

Answer 1

import java.util.*;
import java.lang.*;
import java.io.*;

class Solution {

// YOUR STACK TO USE FOR THIS PROBLEM
private Stack<Integer> pushStack = new Stack<Integer>();
private Stack<Integer> popStack = new Stack<Integer>();

/* =====================================
/* !!! DO NOT MODIFY ABOVE THIS LINE!!!
/* ==================================== */

// This is going to add an elemnt at top of the stack
public void add(int x) {
while (!pushStack.isEmpty())
{
popStack.push(pushStack.pop());
}
  
pushStack.push(x);
  
while (!popStack.isEmpty())
{
pushStack.push(popStack.pop());
}
}
// This is going to remove an element from the top of the stack
public int remove() {

// if first stack is empty
if (pushStack.isEmpty())
{
System.out.println("Q is Empty");
return -1;
}
  
// Return top of pushStack
int x = pushStack.peek();
pushStack.pop();
return x;
}
// This shows the top most element from the stack wothout popping it
public int peek() {
Integer peek_element = (Integer) pushStack.lastElement();
return peek_element;
}
// isEmpty is not directly a part of the Stack but rather implementation from
// Vector. Check if the element exist inside the Stack/Vector or not.
public boolean isEmpty() {
return pushStack.isEmpty();
}
}

public class HomeworkAssignment5_1
{
   public static void main (String[] args) throws java.lang.Exception
   {
       // your code goes here
       Solution sol = new Solution();
sol.add(8);
sol.add(1);
System.out.println(sol.peek());
System.out.println(sol.remove());   
System.out.println(sol.isEmpty());
System.out.println(sol.remove());
System.out.println(sol.isEmpty());
sol.add(2);   
sol.add(3);
System.out.println(sol.peek());
   }
}