力扣刷题记录28.1-----232. 用栈实现队列

---

一、题目

二、代码

class MyQueue {
public:
    
    stack<int> stack_true;  //真实用于模拟队列的堆栈   这个堆栈从顶向下应该就是队列的头到尾
    stack<int> stack_help;  //辅助堆栈
    int first_num=0;

    MyQueue() {
        
    }
    
    void push(int x) {
     
     while(!stack_true.empty()) //当模拟堆栈不为空的时候   一个一个都压入到help中
     {
      stack_help.push(stack_true.top());    
      stack_true.pop();  
     }

     stack_true.push(x);  //把新的数值放在最底下
     
     while(!stack_help.empty())  // 再把数值装回去
     {
        stack_true.push(stack_help.top());    
        stack_help.pop(); 
     }

    }
    
    int pop() {
    
    first_num= stack_true.top();  //取出该数值
    stack_true.pop();             //将其从堆栈中移除
    return first_num;

    }
    
    int peek() {
    
    return stack_true.top();
    }
    
    bool empty() {
    
    
    return stack_true.empty();
    }
};

/**
 * Your MyQueue object will be instantiated and called as such:
 * MyQueue* obj = new MyQueue();
 * obj->push(x);
 * int param_2 = obj->pop();
 * int param_3 = obj->peek();
 * bool param_4 = obj->empty();
 */

三、运行结果