题目：

题解：

class MyQueue {
private:stack<int> inStack, outStack;void in2out() {while (!inStack.empty()) {outStack.push(inStack.top());inStack.pop();}}public:MyQueue() {}void push(int x) {inStack.push(x);}int pop() {if (outStack.empty()) {in2out();}int x = outStack.top();outStack.pop();return x;}int peek() {if (outStack.empty()) {in2out();}return outStack.top();}bool empty() {return inStack.empty() && outStack.empty();}
};