add queue

Author: dmitrymorozoff

README.md

@@ -8,4 +8,5 @@
 3. [Сортировка подсчётом](https://github.com/dmitrymorozoff/algorithms-in-javascript/blob/master/source/sorts/counting-sort.js)
 
 ## Структуры данных
-1. [Стек](https://github.com/dmitrymorozoff/algorithms-in-javascript/blob/master/source/structures/stack.js)
+1. [Стек](https://github.com/dmitrymorozoff/algorithms-in-javascript/blob/master/source/structures/stack.js)
+2. [Очередь](https://github.com/dmitrymorozoff/algorithms-in-javascript/blob/master/source/structures/queue.js)

index.html

@@ -13,6 +13,7 @@
     <script src="./source/sorts/counting-sort.js" type="modul≠e"></script>
     <script src="./source/sorts/selection-sort.js" type="module"></script>
     <script src="./source/structures/stack.js" type="module"></script>
+    <script src="./source/structures/queue.js" type="module"></script>
     <script src="./source/main.js" type="module"></script>
 </body>
 

source/structures/queue.js

@@ -0,0 +1,54 @@
+class Node {
+    constructor(data) {
+        this.data = data;
+        this.next = null;
+    }
+}
+
+export default class Queue {
+    constructor(data) {
+        this.head = null;
+        this.size = 0;
+    }
+    enqueue(data) {
+        const newNode = new Node(data);
+        if (this.head === null && this.size < 1) {
+            this.head = newNode;
+        } else {
+            newNode.next = this.head;
+            this.head = newNode;
+        }
+        this.size++;
+    }
+    dequeue() {
+        if (this.size === 0) {
+            return;
+        }
+        if (this.size === 1) {
+            return this.head;
+        }
+        let current = this.head;
+        while (current.next.next !== null) {
+            current = current.next;
+        }
+        this.last = current;
+        let popElement = current.next;
+        current.next = null;
+        this.size--;
+        return popElement;
+    }
+    peek() {
+        let current = this.head;
+        while (current.next !== null) {
+            current = current.next;
+        }
+        return current;
+    }
+    print() {
+        let iterator = this.head;
+        while (iterator !== null) {
+            console.log(iterator.data);
+            iterator = iterator.next;
+        }
+    }
+}

source/structures/stack.js

@@ -33,7 +33,6 @@ export default class Stack {
         if (this.size === 1) {
             return this.head;
         }
-
         let current = this.head;
         while (current.next.next !== null) {
             current = current.next;