参考回答：
class Solution{public:void push(int node) {stack1.push(node);}int pop() {if(stack2.size()!=0){int tmp = stack2.top();stack2.pop();return tmp;}else{while(stack1.size()!=0){int tmp = stack1.top();stack1.pop();stack2.push(tmp);}return pop();}} private:stack<int> stack1;stack<int> stack2; }；
