题解 | #用两个栈实现队列#

class Solution
{
public:
    void push(int node) {
        if(stack2.size()>0){
            while(!stack2.empty()){
                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;
};