Given a Queue data structure that supports standard operations like enqueue() and dequeue(). The task is to implement a Stack data structure using only instances of Queue and Queue operations allowed on the instances.

Amazon

Senior Software Engineer

Implement Stack using Queues

Implement a queue using a linked list. A queue is a linear data structure that serves as a collection of elements, with three main operations: enqueue, dequeue and peek.

Queue Implementation using a Linked List

We are given the total possible page numbers that can be referred to. We are also given a cache (or memory) size (The number of page frames that the cache can hold at a time). The LRU caching scheme is to remove the least recently used frame when the cache is full and a new page is referenced which is not there in the cache.

LRU Cache Implementation

**The following are the programming based application of queue :** 

**Multi programming**: Multi programming means when multiple programs are running in the main memory. It is essential to organize these multiple programs and these multiple programs are organized as queues. 

**Network:** In a network, a queue is used in devices such as a router or a switch. another application of a queue is a mail queue which is a directory that stores data and controls files for mail messages.

**Job Scheduling:** The computer has a task to execute a particular number of jobs that are scheduled to be executed one after another. These jobs are assigned to the processor one by one which is organized using a queue.

**Shared resources:** Queues are used as waiting lists for a single shared resource.



**Real-time application of Queue:**

1. 1. ATM Booth Line
2. 2. Ticket Counter Line
3. 3. Key press sequence on the keyboard
4. 4. CPU task scheduling
5. 5. Waiting time of each customer at call centers.

Top Queue Interview Questions

1. Implement Stack using Queues

2. Queue Implementation using a Linked List

3. LRU Cache Implementation

4. Application of queue data structure