题解 | #用两个栈实现队列#

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

    int pop() {
        if(stack2.size()){
            int val=stack2.top();
            stack2.pop();
            return val;
        } else{
            while(stack1.size()){
                stack2.push(stack1.top());
                stack1.pop();
            }
            return pop();
        }
    }

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

思路：每一次入队操作变成stack1的入栈，出队操作从stack2出栈，如果stack2为空考虑stack1的内容转移至stack2