Implement a queue and run a list of operations on it. ops[i] is one of "enqueue" (add args[i] at the back), "dequeue" (remove and report the front item, or −1 if empty), "front" (report the front item without removing it, or −1), "isEmpty" (report 1 or 0) and "size". Return everything reported, in order — "enqueue" reports nothing. A queueQueueA first-in, first-out (FIFO) collection: items join at the back and leave from the front. works like a line of people: the first to arrive is the first served. Storing it in an array raises a practical question — what happens to the empty slot at the front after a dequeue? Shifting everything left is easy but slow; moving a head indexHead IndexAn index that marks where the front of a queue currently is inside its array. instead makes every operation O(1).