Add day 41

Author: MadhavBahl

README.md

@@ -68,6 +68,7 @@ Motivate yourself to code daily till 60 days, and see the magic! Coding will bec
 | [Day 38](./day38) | [Implement Stack Data Structure](./day38) | [http://codetoexpress.tech/dc/day38/](http://codetoexpress.tech/dc/day38/) | **Beginner** |
 | [Day 39](./day39) | [Maximum Element and Reverse Stack](./day39) | [http://codetoexpress.tech/dc/day39/](http://codetoexpress.tech/dc/day39/) | **Intermediate** |
 | [Day 40](./day40) | [Prefix, Infix, Postfix Conversion](./day40) | [http://codetoexpress.tech/dc/day40/](http://codetoexpress.tech/dc/day40/) | **Intermediate** |
+| [Day 41](./day41) | [Implement Queue Data Structure](./day41) | [http://codetoexpress.tech/dc/day41/](http://codetoexpress.tech/dc/day41/) | **Beginner** |
 
 ## [More Problems](./BONUS/README.md)
 

day39/ques.png

@@ -0,0 +1,52 @@
+/**
+ * Implementation of queue usinig JS
+ * @author MadhavBahlMD
+ * @date 14/02/2019
+ */
+
+class Queue {
+    constructor (size) {
+        this.capacty = size;
+        this.data = [];
+        this.frontIndex = 0;
+        this.rearIndex = 0;
+    }
+
+    front () {
+        return data[this.frontIndex];
+    }
+
+    rear () {
+        return data[this.rearIndex];
+    }
+
+    enqueue (element) {
+        if (this.rearIndex >= this.capacty)  {
+            console.log ("Overflow!");
+            return -1;
+        }
+        this.data.unshift (element);
+        console.log (element + ' added to the queue');
+        this.rearIndex++;
+    }
+
+    dequeue (element) {
+        if (this.rearIndex === 0) {
+            console.log ("Underflow!");
+            return -1;
+        }
+        console.log (this.data[this.rearIndex -1] + ' has been removed from the queue');
+        this.rearIndex--;
+        return this.data.pop ();
+    }
+}
+
+const myQ = new Queue (4);
+
+myQ.dequeue ( );
+myQ.enqueue (1);
+myQ.enqueue (2);
+myQ.enqueue (3);
+myQ.enqueue (4);
+myQ.enqueue (5);
+myQ.dequeue ( );

day40/JavaScript/queue.js

@@ -0,0 +1,79 @@
+![cover](./cover.png)
+
+# Day 41 - Implement a Queue
+
+Just like a stack, queue is also a linear data structure which follows a particular order in which the operations are performed. The order is called FIFO (First In First Out) which means the first element to enter the queue will be the last one to exit
+
+There are many real-life examples of a queue, and the most common one of them is the real queue. It can be a queue of people waiting at billing counter, or a queue of people waiting at a ticket counter etc.
+
+A Queue has various methods -
+
+1. `Enqueue()` - **Adds an item to the queue**
+2. `Dequeue()` - **Removes an item from the queue**
+3. `Front()` - **Get the front item from queue**
+4. `Rear()` - **Get the last item from queue**
+
+Try to implement a queue 😁
+
+Read more about queues here: https://www.geeksforgeeks.org/queue-set-1introduction-and-array-implementation/
+
+## Solution
+
+## JavaScript Implementation
+
+### [Solution](./JavaScript/queue.js)
+
+```js
+/**
+ * Implementation of queue usinig JS
+ * @author MadhavBahlMD
+ * @date 14/02/2019
+ */
+
+class Queue {
+    constructor (size) {
+        this.capacty = size;
+        this.data = [];
+        this.frontIndex = 0;
+        this.rearIndex = 0;
+    }
+
+    front () {
+        return data[this.frontIndex];
+    }
+
+    rear () {
+        return data[this.rearIndex];
+    }
+
+    enqueue (element) {
+        if (this.rearIndex >= this.capacty)  {
+            console.log ("Overflow!");
+            return -1;
+        }
+        this.data.unshift (element);
+        console.log (element + ' added to the queue');
+        this.rearIndex++;
+    }
+
+    dequeue (element) {
+        if (this.rearIndex === 0) {
+            console.log ("Underflow!");
+            return -1;
+        }
+        console.log (this.data[this.rearIndex -1] + ' has been removed from the queue');
+        this.rearIndex--;
+        return this.data.pop ();
+    }
+}
+
+const myQ = new Queue (4);
+
+myQ.dequeue ( );
+myQ.enqueue (1);
+myQ.enqueue (2);
+myQ.enqueue (3);
+myQ.enqueue (4);
+myQ.enqueue (5);
+myQ.dequeue ( );
+```