P

```
/**
* This is an array-based implementation of a Queue.
* A Queue is a data structure that follows the FIFO (First In First Out) principle.
* It means that the first element that was added to the queue will be the first one to be removed.
* The time complexity of the operations is O(n).
*/
import { Queue } from './queue'
export class ArrayQueue<T> implements Queue<T>{
private queue: T[] = [];
/**
* Returns the number of items in the queue.
*
* @returns {number} The number of items in the queue.
*/
length(): number {
return this.queue.length;
}
/**
* Checks if the queue is empty.
*
* @returns {boolean} Whether the queue is empty or not.
*/
isEmpty(): boolean {
return this.queue.length === 0;
}
/**
* Adds an item to the queue.
*
* @param item The item being added to the queue.
*/
enqueue(item: T): void {
this.queue.push(item);
}
/**
* Removes an item from the queue and returns it.
*
* @throws Queue Underflow if the queue is empty.
* @returns The item that was removed from the queue.
*/
dequeue(): T {
if (this.isEmpty()) {
throw new Error("Queue Underflow");
}
return this.queue.shift() as T;
}
/**
* Returns the item at the front of the queue.
*
* @returns The item at the front of the queue or null if the queue is empty.
*/
peek(): T | null {
if (this.isEmpty()) {
return null;
}
return this.queue[0];
}
}
```