Queue and Stack

Author: emon535

Algorithm/Queue/Queue.js

@@ -0,0 +1,41 @@
+class Queue {
+  // Array is used to implement a Queue
+  constructor() {
+    this.items = [];
+  }
+
+  // enqueue function
+  enqueue(element) {
+    // adding element to the queue
+    this.items.push(element);
+  }
+
+  // dequeue function
+  dequeue() {
+    // removing element from the queue
+    // returns underflow when called
+    // on empty queue
+    if (this.isEmpty()) return "Underflow";
+    return this.items.shift();
+  }
+
+  front() {
+    // returns the Front element of
+    // the queue without removing it.
+    if (this.isEmpty()) return "No elements in Queue";
+    return this.items[0];
+  }
+
+  // isEmpty function
+  isEmpty() {
+    // return true if the queue is empty.
+    return this.items.length == 0;
+  }
+
+  // printQueue()
+  printQueue() {
+    var str = "";
+    for (var i = 0; i < this.items.length; i++) str += this.items[i] + " ";
+    return str;
+  }
+}

Algorithm/Stack/Stack.js

@@ -0,0 +1,42 @@
+class Stack {
+  // Array is used to implement stack
+  constructor() {
+    this.items = [];
+  }
+
+  // Functions to be implemented
+  // push(item)
+  push(element) {
+    // push element into the items
+    this.items.push(element);
+  }
+
+  // pop()
+  pop() {
+    // return top most element in the stack
+    // and removes it from the stack
+    // Underflow if stack is empty
+    if (this.items.length == 0) return "Underflow";
+    return this.items.pop();
+  }
+
+  // peek()
+  peek() {
+    // return the top most element from the stack
+    // but does'nt delete it.
+    return this.items[this.items.length - 1];
+  }
+
+  // isEmpty()
+  isEmpty() {
+    // return true if stack is empty
+    return this.items.length == 0;
+  }
+
+  // printStack()
+  printStack() {
+    var str = "";
+    for (var i = 0; i < this.items.length; i++) str += this.items[i] + " ";
+    return str;
+  }
+}