fix: change in Queue APIs

Author: ashokdey

src/_DataStructures_/LinkedList/index.js

@@ -22,13 +22,16 @@ class LinkedList {
   }
 
   addAtEnd(element) {
+    const node = new Node(element, null);
+    this.size += 1;
+
     if (!this.head) {
-      return this.addAtBeginning(element);
+      this.head = node;
+      this.tail = node;
+      return node;
     }
-    const node = new Node(element, null);
     this.tail.next = node;
     this.tail = node;
-    this.size += 1;
     return node;
   }
 
@@ -42,6 +45,7 @@ class LinkedList {
     const node = this.head;
     this.head = this.head.next;
     this.size -= 1;
+    node.next = null;
     return node;
   }
 
@@ -139,6 +143,7 @@ class LinkedList {
     const node = address;
     previous.next = address.next.next;
     this.size -= 1;
+    node.next = null;
     return node;
   }
 

src/_DataStructures_/Queue/Queue.test.js

@@ -12,9 +12,9 @@ describe('Data Structure : Queue', () => {
       queue = new Queue();
     });
 
-    it('Should enqueue() element to a queue', () => {
+    it('Should add element to a queue', () => {
       queue.enqueue(5);
-      expect(queue.peek()).toEqual([5]);
+      expect(queue.peek()).toEqual(5);
     });
 
     it('Should dequeue() an element from the queue', () => {
@@ -23,7 +23,7 @@ describe('Data Structure : Queue', () => {
 
       expect(queue.dequeue()).toEqual(2);
       expect(queue.peek()).toEqual(3);
-      expect(queue.size()).toEqual(1);
+      expect(queue.length()).toEqual(1);
     });
 
     describe('peek()', () => {
@@ -38,21 +38,21 @@ describe('Data Structure : Queue', () => {
 
       it('Should not remove the element', () => {
         expect(queue.peek()).toEqual(2);
-        expect(queue.remove()).toEqual(2);
+        expect(queue.dequeue()).toEqual(2);
       });
     });
 
     it('Should maintain the order of elements', () => {
       // first in first out
-      queue.add(2);
-      queue.add(1);
-      queue.add(4);
-      queue.add(3);
-
-      expect(queue.remove()).toEqual(2);
-      expect(queue.remove()).toEqual(1);
-      expect(queue.remove()).toEqual(4);
-      expect(queue.remove()).toEqual(3);
+      queue.enqueue(2);
+      queue.enqueue(1);
+      queue.enqueue(4);
+      queue.enqueue(3);
+
+      expect(queue.dequeue()).toEqual(2);
+      expect(queue.dequeue()).toEqual(1);
+      expect(queue.dequeue()).toEqual(4);
+      expect(queue.dequeue()).toEqual(3);
     });
   });
 });

src/_DataStructures_/Queue/index.js

@@ -7,8 +7,7 @@ class Queue extends SinglyLinkedLists {
   }
 
   enqueue(data) {
-    const node = new Node(data, null);
-    return this.addAtEnd(node);
+    return this.addAtEnd(data);
   }
 
   dequeue() {
@@ -17,11 +16,12 @@ class Queue extends SinglyLinkedLists {
   }
 
   peek() {
-    return this.getFirst();
+    const node = this.getFirst();
+    return node.data;
   }
 
-  size() {
-    return this.length();
+  length() {
+    return this.size;
   }
 
   destroy() {
@@ -54,4 +54,13 @@ class Queue extends SinglyLinkedLists {
   }
 }
 
+const q = new Queue();
+
+q.enqueue(10);
+q.enqueue(101);
+q.enqueue(44);
+
+console.log(q.length());
+console.log(q.dequeue());
+
 module.exports = Queue;