Implement Queue using Stacks (Round 2, LC 232:)

Problem Overview

• Build a FIFO queue using only two stacks; implement MyQueue with push(x), pop(), peek(), and empty().
• Constraints: x in 1–9, up to 100 operations; pop and peek are always valid; only standard stack ops allowed.
• Domain: data structures design; queue via stacks used in software systems.
• From Microsoft interviews: a coding interview problem (LC 232) and a common interview question.