Create Priority_queue.js (#752)

Priority_Queue/Priority_Queue.js

@@ -0,0 +1,87 @@
+class queueElement {
+    constructor(element, priority) {
+        this.element = element;
+        this.prioriry = priority;
+    }
+}
+
+class PriorityQueue {
+    constructor() {
+        this.items = [];
+    }
+
+    //to add an element to the queue
+    enqueue(element, priority) {
+        var newQueueElement = new queueElement(element, priority);
+        var isPresent = false;
+        for (let i = 0; i < this.items.length; i++) {
+            if (this.items[i].priority > newQueueElement.priority) {
+                this.items.splice(i, 0, newQueueElement);
+                isPresent = true;
+                break;
+            }
+        }
+        if (!isPresent) {
+            this.items.push(newQueueElement);
+        }
+    }
+
+    //to remove element form a queue
+    dequeue() {
+        if (this.isEmpty()) {
+            return "Underflow";
+        }
+        return this.items.shift();
+    }
+
+    //the front function
+    //returns the highest priority elemnt of queue
+    front() {
+        if (this.isEmpty()) {
+            return "Empty Queue";
+        }
+        return this.items[0];
+    }
+    //the rear function
+    // returns the lowest priorty element of the queue 
+    rear() {
+        if (this.isEmpty()) {
+            return "Empty Queue";
+        }
+        return this.items[this.items.length - 1];
+    }
+    // isEmpty function 
+    isEmpty() {
+        return this.items.length == 0; //true if queue is empty
+    }
+    // printQueue function 
+
+    printPriorityQueue() {
+        var string = "";
+        for (var i = 0; i < this.items.length; i++)
+            string += this.items[i].element + " ";
+        return string;
+    }
+}
+
+var newPriorityQueue = new PriorityQueue();
+newPriorityQueue.enqueue("1", 1);
+newPriorityQueue.enqueue("2", 2);
+newPriorityQueue.enqueue("3", 3);
+newPriorityQueue.enqueue("4", 4);
+newPriorityQueue.enqueue("5", 5);
+console.log(newPriorityQueue.printPriorityQueue());
+console.log(newPriorityQueue.front().element);
+console.log(newPriorityQueue.rear().element);
+console.log(newPriorityQueue.dequeue().element);
+//After dequeue
+console.log(newPriorityQueue.printPriorityQueue());
+
+
+//OUTPUT =>
+
+// 1 2 3 4 5 
+// 1
+// 5
+// 1
+// 2 3 4 5