zoukankan      html  css  js  c++  java
  • [LeetCode-JAVA] Implement Stack using Queues

    题目:

    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 backpeek/pop from frontsize, 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).

    题意:用queue来模拟stack,用queue的基本操作

    思路:比较简单,用两个queue来进行即可,一个作为模拟的stack存储,一个运来转换中间的操作数字

    代码:

    class MyStack {
        LinkedList<Integer> queue = new LinkedList<Integer>();
        LinkedList<Integer> temp = new LinkedList<Integer>();
        // Push element x onto stack.
        public void push(int x) {
            while(!queue.isEmpty()){
                temp.offer(queue.poll());
            }
            queue.offer(x);
            while(!temp.isEmpty()){
                queue.offer(temp.poll());
            }
        }
    
        // Removes the element on top of the stack.
        public void pop() {
            queue.poll();
        }
    
        // Get the top element.
        public int top() {
            return queue.peek();
        }
    
        // Return whether the stack is empty.
        public boolean empty() {
            return queue.isEmpty();
        }
    }
  • 相关阅读:
    排序算法
    存储5——逻辑卷管理LVM
    php && 逻辑与运算符使用说明
    php分页代码
    PHP中获取当前页面的完整URL
    php 文件上传后缀名与文件类型对照表(几乎涵盖所有文件)
    生成订单唯一id
    JS 返回上一步(退回上一步上一个网页)
    php实现的太平洋时间和北京时间互转的自定义函数
    php 上传视频的代码
  • 原文地址:https://www.cnblogs.com/TinyBobo/p/4590385.html
Copyright © 2011-2022 走看看