AcWing 20. 用两个栈实现队列（C++）- 一个作输入栈，一个作输出栈

妖狐艹你老母 2022-08-28 11:48 108阅读 0赞

题目链接：[https://www.acwing.com/problem/content/description/36/][https_www.acwing.com_problem_content_description_36]  
题目如下：  
![在这里插入图片描述][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASkluZ2xlczEyMw_size_20_color_FFFFFF_t_70_g_se_x_16]

class MyQueue {
        
    public:
        stack<int> stk1;
        stack<int> stk2;
        /** Initialize your data structure here. */
        MyQueue() {
        
            
        }
        
        /** Push element x to the back of queue. */
        void push(int x) {
        
            stk1.push(x);
        }
        
        /** Removes the element from in front of queue and returns that element. */
        int pop() {
        
            while(!stk1.empty()){
        
                stk2.push(stk1.top());
                stk1.pop();
            }
            
            int num=stk2.top();
            stk2.pop();
            while(!stk2.empty()){
        
                stk1.push(stk2.top());
                stk2.pop();
            }
            
            return num;
        }
        
        /** Get the front element. */
        int peek() {
        
            while(!stk1.empty()){
        
                stk2.push(stk1.top());
                stk1.pop();
            }
            
            int num=stk2.top();
            while(!stk2.empty()){
        
                stk1.push(stk2.top());
                stk2.pop();
            }
            
            return num;
        }
        
        /** Returns whether the queue is empty. */
        bool empty() {
        
            return stk1.empty();
        }
    };
    
    /**
     * Your MyQueue object will be instantiated and called as such:
     * MyQueue obj = MyQueue();
     * obj.push(x);
     * int param_2 = obj.pop();
     * int param_3 = obj.peek();
     * bool param_4 = obj.empty();
     */

[https_www.acwing.com_problem_content_description_36]: https://www.acwing.com/problem/content/description/36/
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASkluZ2xlczEyMw_size_20_color_FFFFFF_t_70_g_se_x_16]: /images/20220828/05a0d26e496e4e88aa65a0596ab4dfe2.png