题解 | #用两个栈实现队列#

1.stack1进，stack2出

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

    int pop() {
        if(stack2.size()>0) {
            int res = stack2.top();
            stack2.pop();
            return res;
        } else {
            while(stack1.size()>0) {
                int x = stack1.top();
                stack2.push(x);
                stack1.pop();
            }
            int res = stack2.top();
            stack2.pop();
            return res;
        }
    }

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