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Commit 417287a

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Queues
1 parent 9276de7 commit 417287a

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4 files changed

+197
-0
lines changed

4 files changed

+197
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lines changed

‎#5 - Queue/0-queue-implementation.js‎

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// Basic Queue Implementation
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class Queue {
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constructor() {
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this.queue = [];
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}
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enqueue(element) {
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this.queue.push(element);
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}
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dequeue() {
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if (this.isEmpty()) {
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return "Underflow, cannot perform dequeue";
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}
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return this.queue.shift();
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}
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isEmpty() {
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return this.size() === 0;
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}
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front() {
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if (this.isEmpty()) {
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return "No Elements in the Queue";
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}
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return this.queue[0];
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}
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size() {
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return this.queue.length;
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}
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printQueue() {
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let queueString = "";
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for (let i = 0; i < this.size(); i++) {
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queueString += this.queue[i] + ", ";
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}
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console.log("Queue: " + queueString);
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}
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}
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const myQueue = new Queue();
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myQueue.enqueue(5);
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myQueue.enqueue(96);
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myQueue.enqueue(786);
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myQueue.dequeue();
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myQueue.dequeue();
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myQueue.dequeue();
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console.log(myQueue.dequeue());
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console.log(myQueue.front());

‎#5 - Queue/1-circular-queue.js‎

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// Ques 1 : Circular Queue Implementation
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// Design your implementation of the circular queue. The circular queue is a
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// linear data structure in which the operations are performed based on First In First Out
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// principle, and the last position is connected back to the first position to make a circle.
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var MyCircularQueue = function (k) {
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this.queue = [];
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this.size = k;
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};
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MyCircularQueue.prototype.enQueue = function (value) {
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if (this.size === this.queue.length) return false;
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this.queue.push(value);
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return true;
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};
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MyCircularQueue.prototype.deQueue = function () {
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if (this.queue.length === 0) return false;
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this.queue.shift();
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return true;
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};
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MyCircularQueue.prototype.Front = function () {
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if (this.queue.length === 0) return -1;
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return this.queue[0];
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};
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MyCircularQueue.prototype.Rear = function () {
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if (this.queue.length === 0) return -1;
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return this.queue[this.queue.length - 1];
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};
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MyCircularQueue.prototype.isEmpty = function () {
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return this.queue.length === 0;
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};
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MyCircularQueue.prototype.isFull = function () {
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return this.size === this.queue.length;
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};
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// [2,5,72]
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var obj = new MyCircularQueue(3);
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obj.enQueue(1);
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obj.enQueue(4);
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obj.enQueue(2);
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obj.deQueue();
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obj.enQueue(5);
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obj.deQueue();
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obj.enQueue(72);
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console.log(obj.Front(), obj.Rear());
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// Ques 2 : Implement Stack using Queues
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// Implement a last -in -first - out(LIFO) stack using only two queues.
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// The implemented stack should support all the functions of a stack (push, top, pop, and empty).
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var MyStack = function () {
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this.q1 = [];
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this.q2 = [];
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};
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// q1 - [4,2,3,5]
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// q2 - []
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MyStack.prototype.push = function (x) {
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while (this.q1.length !== 0) {
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this.q2.push(this.q1.shift());
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}
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this.q1.push(x);
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while (this.q2.length !== 0) {
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this.q1.push(this.q2.shift());
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}
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};
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MyStack.prototype.pop = function () {
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return this.q1.shift();
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};
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MyStack.prototype.top = function () {
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return this.q1[0];
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};
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MyStack.prototype.empty = function () {
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return this.q1.length === 0;
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};
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var stack = new MyStack();
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stack.push(3);
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stack.push(5);
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stack.push(96);
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stack.push(24);
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stack.pop();
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console.log(stack.top());
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// Ques 3 : Implement Queue using Stacks
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// Implement a first in first out(FIFO) queue using only two stacks.
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// The implemented queue should have all functions of queue(enqueue, front, dequeue, and empty).
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var MyQueue = function () {
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this.stack1 = [];
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this.stack2 = [];
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};
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MyQueue.prototype.enqueue = function (x) {
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this.stack1.push(x);
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};
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// stack1 = [9,10]
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// stack2 = []
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MyQueue.prototype.dequeue = function () {
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if (this.stack2.length === 0) {
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while (this.stack1.length > 0) {
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this.stack2.push(this.stack1.pop());
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}
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}
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return this.stack2.pop();
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};
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MyQueue.prototype.front = function () {
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if (this.stack2.length === 0) {
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while (this.stack1.length > 0) {
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this.stack2.push(this.stack1.pop());
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}
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}
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return this.stack2[this.stack2.length - 1];
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};
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MyQueue.prototype.empty = function () {
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return this.stack1.length === 0 && this.stack2.length === 0;
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};
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[3, 6, 7];
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const queue = new MyQueue();
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queue.enqueue(3);
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queue.enqueue(6);
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queue.enqueue(7);
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queue.dequeue();
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console.log(queue.front());

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