Implementation of Stack using Queue Algorithm and Flowchart

(216 Views)


What is Implementation of Stack using Queue?

The problem is opposite of this post. We are given a stack data structure with a push and pop operations, the task is to implement a queue using instances of stack data structure and operations on them.

Implementation of Stack using Queue

Image Reference: Geeks for Geeks

Flow Chart for Implementation of Stack using Queue:

Flow Chart for Implementation of Stack using Queue

Image Reference: leetcode.com

Pseudocode for Implementation of Stack using Queue:

enQueue(q, x): While the stack1 is not empty, push everything from stack1 to stack2. Push the value of x to stack1 (assuming size of stacks is unlimited). Push everything back to stack1. Here time complexity will be O(n) deQueue(q): If stack1 is empty then error Pop an item from stack1 and return it Here time complexity will be O(1)

Implementation of Stack using Queue Implementation in Java

import java.util.*; class GFG { static class Queue { static Stack<Integer> s1 = new Stack<Integer>(); static Stack<Integer> s2 = new Stack<Integer>(); static void enQueue(int x) { // Move all elements from s1 to s2 while (!s1.isEmpty()) { s2.push(s1.pop()); //s1.pop(); } // Push item into s1 s1.push(x); // Push everything back to s1 while (!s2.isEmpty()) { s1.push(s2.pop()); //s2.pop(); } } // Dequeue an item from the queue static int deQueue() { // if first stack is empty if (s1.isEmpty()) { System.out.println("Q is Empty"); System.exit(0); } // Return top of s1 int x = s1.peek(); s1.pop(); return x; } }; // Driver code public static void main(String[] args) { Queue q = new Queue(); q.enQueue(1); q.enQueue(2); q.enQueue(3); System.out.println(q.deQueue()); System.out.println(q.deQueue()); System.out.println(q.deQueue()); } }

Output of the above program

1 2 3

Solution Worked 0 UpvotesUpvote

        

Solution Didn't Worked 0 DownvotesDownvote



Comments



Search

Play 2048 Game Online

Play Duckhunt Online

Need Help?

Looking for any Software or Tutorial?
Don't Worry, we will find it for you
Contact Now

Search Tags

    Stack using Queue Algorithm

    Stack using Queue Pseudocode

    Stack using Queue Algorithm implementation in Java