Implement Queue Using Stacks

Implement a first-in-first-out (FIFO) queue using only two stacks. Implement MyQueue() and: - push(x): Push x to the back of the queue. - pop(): Remove and return the element from the front. - peek(): Return the element at the front without removing. - empty(): Return true if the queue is empty. DE Shaw Tier 2 — LC 232. Optimal: Two stacks (inbox/outbox). Push always goes to inbox. Pop/peek: if outbox is empty, pour inbox into outbox (reversing order). Amortized O(1) per operation. Talk-track: 'Each element is moved at most twice — once into inbox, once into outbox. Total work is O(n), amortized O(1).'