栈实现队列
请你仅使用两个栈实现先入先出队列。队列应当支持一般队列支持的所有操作（push、pop、peek、empty）：
实现 MyQueue 类：
void push(int x)将元素 x 推到队列的末尾int pop()从队列的开头移除并返回元素int peek()返回队列开头的元素boolean empty()如果队列为空，返回true；否则，返回false
class MyQueue {Stack<Integer> stack = new Stack<>();Stack<Integer> tmp = new Stack<>();public MyQueue() {}public void push(int x) {stack.push(x);}public int pop() {tmp.empty();while(!stack.empty()){tmp.push(stack.peek());stack.pop();}Integer res = tmp.pop();while(!tmp.empty()){stack.push(tmp.peek());tmp.pop();}return res;}public int peek() {tmp.empty();while(!stack.empty()){tmp.push(stack.peek());stack.pop();}Integer res = tmp.peek();while(!tmp.empty()){stack.push(tmp.peek());tmp.pop();}return res;}public boolean empty() {return stack.empty();}}
用另一个栈实现
