Stack and queue

.eslintrc.json

@@ -0,0 +1,27 @@
+{
+    "env": {
+      "browser": true,
+      "node": true,
+      "commonjs": true,
+      "jest": true,
+      "es6": true
+    },
+    "globals": {
+      "err": true,
+      "req": true,
+      "res": true,
+      "next": true
+    },
+    "extends": "eslint:recommended",
+    "parserOptions": {
+      "sourceType": "module"
+    },
+    "rules": {
+      "no-console": "off",
+      "indent": [ "error", 2 ],
+      "quotes": ["error", "single", { "allowTemplateLiterals": true }],
+      "comma-dangle": ["error", "always-multiline"],
+      "semi": [ "error", "always" ]
+    }
+  }
+

README.md

@@ -1,6 +1,21 @@
-# Table of Contents
-[1- code challange class 2 array shift ](https://github.com/Goorob-401-advanced-javascript/data-structures-and-algorithms/pull/3)
+# Stack and Queue 
+## challange summary 
+stack is a type of data structure that is linear where order is conserved. For many people, stack is known to have a LIFO (Last In First Out) mechanism .
+queue is a linear data structure where it obeys the FIFO (First In First Out) mechanism.
+
+## Challenge description
+1. create a Stack class that has a top property. It creates an empty Stack when instantiated.
+- Define a method called push which takes any value as an argument and adds a new node with that value to the top of the stack with an O(1) Time performance.
+- Define a method called pop that does not take any argument, removes the node from the top of the stack, and returns the node’s value.
+- Define a method called peek that does not take an argument and returns the value of the node located on top of the stack, without removing it from the stack.
+- Define a method called isEmpty that does not take an argument, and returns a boolean indicating whether or not the stack is empty.
+1. Create a Queue class that has a front property. It creates an empty Queue when instantiated.
+- Define a method called enqueue which takes any value as an argument and adds a new node with that value to the back of the queue with an O(1) Time performance.
+- Define a method called dequeue that does not take any argument, removes the node from the front of the queue, and returns the node’s value.
+- Define a method called peek that does not take an argument and returns the value of the node located in the front of the queue, without removing it from the queue.
+- Define a method called isEmpty that does not take an argument, and returns a boolean indicating whether or not the queue is empty.
+
+## Approach & Efficiency
+The Big of O is o(1) for all the method
 
-[2- code challange class 3 array binary search ](https://github.com/Goorob-401-advanced-javascript/data-structures-and-algorithms/pull/2)
 
-[

challanges/stack-and-queue/__test__/queue.test.js

@@ -0,0 +1,35 @@
+'use strict';
+
+const Queue = require('../queue.js');
+
+describe('Queue', () => {
+  it('add item to the end ', () => {
+    let queue = new Queue();
+    queue.enqueue('shoroq');
+    queue.enqueue('goorob');
+    queue.enqueue('duha');
+    expect(queue.front).toEqual('shoroq');
+    expect(queue.rear).toEqual('duha');
+
+  });
+
+  it('remove from the front ', () => {
+    let queue = new Queue();
+    queue.enqueue('shoroq');
+    queue.enqueue('goorob');
+    queue.enqueue('duha');
+    let item = queue.dequeue();
+    expect(item).toEqual('shoroq');
+    expect(queue.front).toEqual('goorob');
+    expect(queue.rear).toEqual('duha');
+    queue.dequeue();
+    queue.dequeue();
+    expect(queue.dequeue()).toBeNull();
+    expect(queue.front).toBeNull();
+    expect(queue.rear).toBeNull();
+  });
+  describe('isEmpty()' , ()=> {
+    let queue = new Queue();
+    expect(queue.isEmpty()).toBeTruthy();
+  });
+});

challanges/stack-and-queue/__test__/stack.test.js

@@ -0,0 +1,45 @@
+'use strict';
+
+const Stack = require('../stack.js');
+
+describe('Stack', () => {
+  describe('push()', () => {
+    it('(add) push an item', () => {
+      let stack = new Stack();
+      expect(stack.peek()).toBeNull();
+      stack.push('Instance');
+      expect(stack.peek()).toEqual('Instance');
+      stack.push('Sally');
+      expect(stack.peek()).toEqual('Sally');
+    });
+  });
+
+  describe('pop()', () => {
+    it('remove the top item ', () => {
+      let stack = new Stack();
+      stack.push('shoroq');
+      stack.push('goorob');
+      stack.push('duha');
+      let item = stack.pop();
+      expect(item).toEqual('duha');
+      stack.pop();
+      item = stack.pop();
+      expect(item).toEqual('shoroq');
+      console.log(stack);
+      expect(stack.peek()).toBeNull();
+    });
+  });
+  describe('peek()', ()=> {
+    it('rturn top of stack', () => {
+      let stack = new Stack();
+      stack.push('shoroq');
+      expect(stack.peek()).toEqual('shoroq');
+    });
+  });
+  describe('isEmpty()' , ()=> {
+    it('should be empty' , () =>{
+      let stack = new Stack();
+      expect(stack.isEmpty()).toBeTruthy();
+    });
+  });
+});

challanges/stack-and-queue/queue.js

@@ -0,0 +1,42 @@
+'use strict';
+
+class Queue {
+  constructor(){
+    this.storage = [];
+    this.front = null;
+    this.rear = null;
+  }
+
+  enqueue(item){
+    this.storage.push(item);
+    if(this.storage.length == 1){
+      this.front = item;
+      this.rear = item;
+    }
+    else{
+      this.rear = item;
+    }
+  }
+
+  dequeue(){
+    if(!this.storage.length){
+      return null;
+    }
+
+    let item = this.storage.shift();
+    if(this.storage.length == 0){
+      this.front = this.rear = null;
+    }
+    else{
+      this.front = this.storage[0];
+      this.rear = this.storage[this.storage.length-1];
+    }
+
+    return item;
+  }
+  isEmpty(){
+    if(this.storage.length == 0){ return true ; }
+  }
+}
+
+module.exports = Queue;

challanges/stack-and-queue/stack.js

@@ -0,0 +1,28 @@
+'use strict';
+
+class Stack{
+  constructor(){
+    this.storage = [];
+    this.top = null;
+  }
+
+  push(item){
+    this.storage.push(item);
+    this.top = item;
+  }
+
+  pop(){
+    let item = this.storage.pop();
+    this.top = !this.storage.length ? null : this.storage[this.storage.length-1];
+    return item;
+  }
+
+  peek(){
+    return this.top;
+  }
+  isEmpty(){
+    if(this.storage.length == 0){ return true ;}
+  }
+}
+
+module.exports = Stack;