题解 | #用两个栈实现队列，比官方题解效率更高#

class Solution
{
public:
    void push(int node) {
        while(!stack2.empty())	//在这里可以减少弹出队列时栈的复制次数
        {
            stack1.push(stack2.top());
            stack2.pop();
        }
        stack1.push(node);
    }

    int pop() {
        while(!stack1.empty())
        {
            stack2.push(stack1.top());
            stack1.pop();
        }
        int res = stack2.top();
        stack2.pop();
        return res;
    }

private:
    stack<int> stack1;
    stack<int> stack2;
};