atopchev/stack-queue

A repo housing a Stack and Queue implementation

Stack & Queue Implementation

This project includes 100% test coverage. Tests belongs to App Academy. Developed using Test Driven Development.

Contains three classes, Node, Stack, and Queue.

class Node {
  constructor(val) {
      this.value = val;
      this.next = null;
  }
}

  class Stack {
    constructor() {
        this.top = null;
        this.bottom = null;
        this.length = 0;
    }
    
    push(val){
        let newNode = new Node(val);
        if (!this.top) {
            [ this.top, this.bottom ] = [ newNode, newNode ];
        } else {
            const oldTop = this.top;
            this.top = newNode;
            this.top.next = oldTop;
        }
        
        return ++this.length;
    }

    pop(){
        if (!this.top) return null;

        const oldTop = this.top;
        if (this.top === this.bottom) {
            [ this.top, this.bottom ] = [ null, null ];
        } else {
            this.top = oldTop.next;
        }
        this.length--;
        return oldTop.value;
    }

    size(){
        return this.length;
    }
 }

class Queue {
    constructor() {
        this.front = null;
        this.back = null;
        this.length = 0;
    }

    enqueue(val) {
        const newNode = new Node(val);
 
        if (!this.back) {
            [ this.front, this.back ] = [ newNode, newNode ];
        } else {
            this.back.next = newNode;
            this.back = newNode;
        }

        return ++this.length;
    }

    dequeue(){
        if (!this.front) return null; 

        let oldFront = this.front; 
        if (this.front === this.back) {
            [this.front, this.back] = [ null, null ];
        } else {
            this.front = oldFront.next;
        }

        this.length--;
        return oldFront.value;
    }

    size(){
        return this.length;
    }
};