Merge pull request TheAlgorithms#15 from Hydro95/Queue

the-codingninja · web-flow · commit 0129ca4eb436 · 2017-10-18T18:32:11.000+05:30
Added Queue Data Structure
diff --git a/Data Structures/Queue/Queue.js b/Data Structures/Queue/Queue.js
@@ -0,0 +1,75 @@
+/* Queue
+* A Queue is a data structure that allows you to add an element to the end of
+* a list and remove the item at the front. A queue follows a "First In First Out"
+* system, where the first item to enter the queue is the first to be removed. This
+* implementation uses an array to store the queue.
+*/
+
+//Functions: enqueue, dequeue, peek, view, length
+
+var Queue = function() {
+
+  //This is the array representation of the queue
+  this.queue = [];
+
+  //Add a value to the end of the queue
+  this.enqueue = function(item) {
+    this.queue[this.queue.length] = item;
+  }
+
+  //Removes the value at the front of the queue
+  this.dequeue = function() {
+    if (this.queue.length === 0) {
+      return "Queue is Empty";
+    }
+
+    var result = this.queue[0];
+    this.queue.splice(0, 1); //remove the item at position 0 from the array
+
+    return result;
+  }
+
+  //Return the length of the queue
+  this.length = function() {
+    return this.queue.length;
+  }
+
+  //Return the item at the front of the queue
+  this.peek = function() {
+    return this.queue[0];
+  }
+
+  //List all the items in the queue
+  this.view = function() {
+    console.log(this.queue);
+  }
+}
+
+//Implementation
+var myQueue = new Queue();
+
+myQueue.enqueue(1);
+myQueue.enqueue(5);
+myQueue.enqueue(76);
+myQueue.enqueue(69);
+myQueue.enqueue(32);
+myQueue.enqueue(54);
+
+myQueue.view();
+
+console.log("Length: " + myQueue.length());
+console.log("Front item: " + myQueue.peek());
+console.log("Removed " + myQueue.dequeue() + " from front.");
+console.log("New front item: " + myQueue.peek());
+console.log("Removed " + myQueue.dequeue() + " from front.");
+console.log("New front item: " + myQueue.peek());
+myQueue.enqueue(55);
+console.log("Inserted 55");
+console.log("New front item: " + myQueue.peek());
+
+for (var i = 0; i < 5; i++) {
+  myQueue.dequeue();
+  myQueue.view();
+}
+
+console.log(myQueue.dequeue());
