LeetCode 09. 用两个栈实现队列(简单）

题目链接：https://leetcode.cn/problems/yong-liang-ge-zhan-shi-xian-dui-lie-lcof/

题解思路： 按照下面的函数设计实现一下就OK，很简单，不写了

代码：

class CQueue {
    stack<int> stack_in,stack_out;//定义栈
public:
    CQueue() {
        
    }
    void appendTail(int value) {
        stack_in.push(value);  //入栈
    }
    int deleteHead() {
        if(!stack_out.empty()){
            int res=stack_out.top();//出栈
            stack_out.pop();
            return res;
        }else{
            while(!stack_in.empty()){
                stack_out.push(stack_in.top());
                stack_in.pop();
            }
            if(!stack_out.empty()){
                int res=stack_out.top();
                stack_out.pop();
                return res;
            }else{
                return -1;
            }
        }
    }
};

/**
 * Your CQueue object will be instantiated and called as such:
 * CQueue* obj = new CQueue();
 * obj->appendTail(value);
 * int param_2 = obj->deleteHead();
 */