用两个栈实现队列

class Solution
{
public:
    void push(int node) {
        stack1.push(node);
    }

    int pop() {
        if(stack2.empty()){
            while(!stack1.empty()){
            int temp = stack1.top();
            stack2.push(temp);
            stack1.pop();
        }
        }
        int res = stack2.top();
        stack2.pop();
        return res;
        
    }
    
private:
    stack<int> stack1;
    stack<int> stack2;
};