Wordllban · Wordllban · Sep 21, 2021 · Sep 21, 2021 · Sep 21, 2021 · Sep 21, 2021
diff --git a/README.md b/README.md
@@ -1,4 +1,25 @@
+# Lab-2
 
-## Algorithms 
+---
 
-   My lab works of Algorithms classes as a student of "Internet of Things" program in Lviv Polytechnic National University.
+## Task
+
+Implement Deque based on Doubly-linked list with basics methods thats belong to data structure.
+
+---
+
+  ### Required methods
+  + Unshift - add element in front
+  + Shift - delete front element and return his value
+  + Push - add element in back
+  + Pop - delete element in back and return his value
+  + isEmpty - check is deque empty    
+
+  ### Code must be covered with tests (60%+)
+
+---
+
+## Installation
+  + Download the project and open index.html file
+  + Click right mouse button and select "Inspect"
+  + Now you can use `list.push(*yourValue*)`, `list.unshift(*yourValue*)`, `list.pop()`, `list.shift()` in console
diff --git a/index.html b/index.html
@@ -0,0 +1,30 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta http-equiv="X-UA-Compatible" content="IE=edge">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Deque</title>
+    <link
+      href="https://cdn.rawgit.com/mochajs/mocha/2.2.5/mocha.css"
+      rel="stylesheet"
+    />
+</head>
+<body>
+    <div id="mocha"></div>
+    <script src="https://cdn.rawgit.com/Automattic/expect.js/0.3.1/index.js"></script>
+    <script src="https://cdn.rawgit.com/chaijs/chai/3.5.0/chai.js"></script>
+    <script src="https://cdn.rawgit.com/mochajs/mocha/2.2.5/mocha.js"></script>
+
+    <script src="main.js"></script>
+    <script>
+      const mocha = window.mocha;
+      mocha.setup("bdd");
+    </script>
+    <script src="tests.js"></script>
+    <script>
+      mocha.checkLeaks();
+      mocha.run();
+    </script>
+</body>
+</html>
diff --git a/main.js b/main.js
@@ -0,0 +1,105 @@
+class Node {
+    constructor(value) {
+        this.value = value;
+        this.prev = null;
+        this.next = null; 
+    }
+}
+
+class DoublyLinkedList {
+    constructor() {
+        this.head = null;
+        this.tail = null;
+        this.length = 0;
+    }
+
+    // add element to the end
+    push(value) {
+        let node = new Node(value)
+        // if list is empty 
+        if(!this.head) {
+            this.head = node;
+            this.tail = node;
+        } else { 
+            let temp = this.tail;
+            this.tail = node;
+            node.prev = temp;
+            temp.next = node;
+        }
+        this.length++;
+        return this;
+    } 
+
+    // delete last element and return his value
+    pop() {
+        let lastElement = this.tail;
+        console.log(lastElement);
+        if(!this.head) return undefined;
+        let temp = this.tail;
+        if(this.length === 1) {
+            this.head = null;
+            this.tail = null;
+        } else {
+            this.tail = temp.prev;
+            this.tail.next = null;
+            temp.prev = null;
+        }
+        this.length--;
+        return lastElement;
+    }
+
+    // add element in front
+    unshift(value) {
+        let node = new Node(value);
+        if(!this.head) {
+            this.head = node;
+            this.tail = node;
+        } else {
+            let temp = this.head;
+            this.head = node;
+            node.next = temp;
+            temp.prev = node;
+        }
+        this.length++;
+        return this;
+    }
+
+    // delete front element and return his value 
+    shift() {
+        let firstElement = this.head;
+        console.log(firstElement);
+        if(!this.head) return undefined;
+        let temp = this.head;
+        if(this.length === 1) {
+            this.head = null;
+            this.tail = null;
+        } else {
+            this.head = temp.next;
+            this.head.prev = null;
+            temp.next = null;
+        }
+        this.length--;
+        return firstElement;
+    }
+
+    // check is deque empty
+    isEmpty() {
+        if(!this.head || !this.tail) {
+            return console.log('Is deque empty', true); 
+        } else {
+            return console.log('Is deque empty', false);
+        }
+    }
+}
+
+
+let list = new DoublyLinkedList;
+
+list.push(1);
+list.push(2);
+list.push(3);
+list.unshift(0); 
+
+list.isEmpty();
+
+console.log('Current deque: ', list);
diff --git a/tests.js b/tests.js
@@ -0,0 +1,23 @@
+const chai = window.chai;
+const assert = chai.assert;
+
+var testingList = new DoublyLinkedList;
+
+testingList.push(1);
+testingList.push(2);
+testingList.push(3);
+var lastElem = testingList.tail;
+var firstElem = testingList.head;
+console.log('Deque for tests: ', testingList);
+
+
+describe('Deque based on doubly linked list', () => {
+    it('should pass all tests', () => {
+        console.log('test pop(): ');
+        assert.equal(testingList.pop(), lastElem); // delete last element and return his value
+        console.log('test shift(): ');
+        assert.equal(testingList.shift(), firstElem); // delete first element and return his value 
+        console.log('test isEmpty(): ');
+        assert.equal(testingList.isEmpty(), console.log(false)); // check is deque empty
+    });
+});