Add Queue.

src/data-structures/queue/Queue.js

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+import LinkedList from '../linked-list/LinkedList';
+
+export default class Queue {
+  constructor() {
+    this.linkedList = new LinkedList();
+  }
+
+  isEmpty() {
+    return !this.linkedList.tail;
+  }
+
+  peek() {
+    if (!this.linkedList.tail) {
+      return null;
+    }
+
+    return this.linkedList.tail.value;
+  }
+
+  add(value) {
+    this.linkedList.append({ value });
+  }
+
+  remove() {
+    const removedTail = this.linkedList.deleteTail();
+    return removedTail ? removedTail.value : null;
+  }
+}

src/data-structures/queue/README.md

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+# Queue
+
+|Operation                  |Complexity         |
+|---------------------------|-------------------|
+|Find                       |O()               |
+|Insert/delete at beginning |O()               |
+|Insert/delete in middle    |O() |
+|Insert/delete at end       |O() |

src/data-structures/queue/__test__/Queue.test.js

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+import Queue from '../Queue';
+
+describe('Queue', () => {
+  it('should create empty queue', () => {
+    const queue = new Queue();
+    expect(queue).not.toBeNull();
+    expect(queue.linkedList).not.toBeNull();
+  });
+
+  it('should add data to queue', () => {
+    const queue = new Queue();
+
+    queue.add(1);
+    queue.add(2);
+
+    expect(queue.linkedList.toString()).toBe('1,2');
+  });
+
+  it('should peek data from queue', () => {
+    const queue = new Queue();
+
+    expect(queue.peek()).toBeNull();
+
+    queue.add(1);
+    queue.add(2);
+
+    expect(queue.peek()).toBe(2);
+    expect(queue.peek()).toBe(2);
+  });
+
+  it('should check if queue is empty', () => {
+    const queue = new Queue();
+
+    expect(queue.isEmpty()).toBeTruthy();
+
+    queue.add(1);
+
+    expect(queue.isEmpty()).toBeFalsy();
+  });
+
+  it('should remove from empty', () => {
+    const queue = new Queue();
+
+    queue.add(1);
+    queue.add(2);
+
+    expect(queue.remove()).toBe(2);
+    expect(queue.remove()).toBe(1);
+    expect(queue.isEmpty()).toBeTruthy();
+  });
+});