Explain the purpose of the program as detail as possible 3%. Develop a solution

ID: 3885114 • Letter: E

Question

Explain the purpose of the program as detail as possible 3%. Develop a solution for the problem and mention algorithm used -12% List data structures to be used in the solution. - 2%. Give a description of how to use the program and expected input/output - 3% For each method, give the pre and post conditions and invariants, if any - 5% Program execution according to the requirements 50% Naming of program as required 5% Useful comments and readability: 20% Write a program to implement a queue using stack. The file name should be MyQueue.java.

Explanation / Answer

Purpose of the program:

Implement a queue data structure using stack data structure.

Solution:

In order to implement queue using stack we need to have two stacks to do the purpose of one queue.

Data Structures : Stack

Program:

import java.util.Scanner;

import java.util.Stack;

public class MyQueue

{

static class Queue

{

Stack<Integer> stack1 ;

Stack<Integer> stack2 ;

}

static void push(Stack<Integer> push_stk, int new_data)

{

push_stk.push(new_data);

}

static int pop(Stack<Integer> pop_stk)

{

if(pop_stk.isEmpty())

{

System.out.println("Stack Overflow");

System.exit(0);

}

return pop_stk.pop();

}

static void Enqueue(Queue que, int x)

{

push(que.stack1, x);

}

static int Dequeue(Queue que)

{

int x;

if(que.stack1.isEmpty() && que.stack2.isEmpty() )

{

System.out.println("Q is empty");

System.exit(0);

}

if(que.stack2.isEmpty())

{

while(!que.stack1.isEmpty())

{

x = pop(que.stack1);

push(que.stack2, x);

}

x = pop(que.stack2);

return x;

}

static void display(Queue myq)

{

int length1=myq.stack1.size();

int length2=myq.stack2.size();

if(length1+length2==0)

{

System.out.println("Queue is empty");

}

else

{

System.out.println("Queue Elements");

for(int i=0;i<length1;i++)

{

System.out.print(myq.stack1.get(i)+" ");

}

for(int i=length2-1;i>=0;i--)

{

System.out.print(myq.stack2.get(i)+" ");

}

System.out.println();

}

public static void main(String args[])

{

Queue myq= new Queue();

myq.stack1 = new Stack<>();

myq.stack2 = new Stack<>();

Scanner scan = new Scanner(System.in);

int choice;

{

System.out.println("1.Insert element to queue ");

System.out.println("2.Delete element from queue ");

System.out.println("3.Display all elements of queue ");

System.out.println("4.Quit ");

System.out.println("Enter your choice : ");

choice = scan.nextInt();

switch (choice)

{

case 1 :

System.out.println("Enter integer element to insert into stack");

Enqueue( myq,scan.nextInt() );

break;

case 2 :

System.out.println("Removed Element = "+ Dequeue(myq) );

break;

case 3 :

display(myq);

break;

case 4 : System.out.println("Quiting");

System.exit(0);

break;

default: System.out.println("Wrong input");

break;

}

}while(choice>0 && choice<5);

}

Output:

1.Insert element to queue

2.Delete element from queue