用两个栈实现队列

class Solution
{
public:
    void push(int node) {
    s1.push(node);
        
    }

    int pop() {
    while(!s1.empty()){
     s2.push(s1.top());
     s1.pop();   
    }int temp=s2.top();
    s2.pop();
    while(!s2.empty()){
        s1.push(s2.top());
        s2.pop();
    }    
    return temp;    
    }

private:
    stack<int> s1;
    stack<int> s2;
};