15算法课程 225. Implement Stack using Queues

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#算法

本文介绍了一种使用双端队列(deque)来实现栈数据结构的方法。通过具体实现push、pop、top和empty四种基本操作，展示了如何利用队列完成栈的功能。此方法仅使用了标准队列操作，包括向后端添加元素、从前端删除元素、检查队列大小以及判断队列是否为空。

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Implement the following operations of a stack using queues.

push(x) -- Push element x onto stack.
pop() -- Removes the element on top of the stack.
top() -- Get the top element.
empty() -- Return whether the stack is empty.

Notes:

You must use only standard operations of a queue -- which means only push to back, peek/pop from front, size, and is empty operations are valid.
Depending on your language, queue may not be supported natively. You may simulate a queue by using a list or deque (double-ended queue), as long as you use only standard operations of a queue.
You may assume that all operations are valid (for example, no pop or top operations will be called on an empty stack).

solution:

采用dqueue的数据结构

code:

class MyStack {
public:
    /** Initialize your data structure here. */
    MyStack() {
        
    }
    deque<int> mystack;
    /** Push element x onto stack. */
    void push(int x) {
        mystack.push_back(x) ;
        
    }
    
    /** Removes the element on top of the stack and returns that element. */
    int pop() {
        int temp = mystack.back();
        mystack.pop_back();
        return temp;
        
        
    }
    
    /** Get the top element. */
    int top() {
        return mystack.back();
        
    }
    
    /** Returns whether the stack is empty. */
    bool empty() {
        return mystack.empty();
        
    }
};