学校网站维护怎么做/seo短视频入口引流

栈（stack）
1概述：
①栈是一个后进先出(LIFO, Last In First Out)的有序列表。
②栈的插入和删除只能在线性表的同一端进行。允许插入和删除的一端称为栈顶(Top)，另一端为固定的一端，称为栈底(Bottom)。
③根据栈的定义可知，最先放入栈中元素在栈底，最后放入的元素在栈顶，而删除元素刚好相反，最后放入的元素最先删除，最先放入的元素最后删除。
④出栈(pop)和入栈(push)的概念(如下图所示)


2. 用数组实现栈

1. 用数组实现栈的思路分析
   ①.定义一个 top 来表示栈顶，初始化为 -1;
   ②. 入栈的操作，当有数据加入到栈时， top++; stack[top] = data;
   ④. 出栈的操作， int value = stack[top]; top–, return value;
   

2.代码实现

public class ArrayStackDemo {public static void main(String[] args) {//创建一个ArrayStack对象表示栈ArrayStack stack = new ArrayStack(4);String key = "";boolean loop = true;//控制是否退出菜单Scanner scanner = new Scanner(System.in);while (loop) {System.out.println("show：显示栈");System.out.println("exit：退出程序");System.out.println("push：入栈");System.out.println("pop：出栈");System.out.println("请输入");key = scanner.next();switch (key) {case "show":stack.list();break;case "push":System.out.println("请输入一个数");int value = scanner.nextInt();stack.push(value);break;case "pop":try {int res = stack.pop();System.out.printf("出栈的数据是%d\n", res);} catch (Exception e) {System.out.println(e.getMessage());}break;case "exit":scanner.close();loop = false;break;default:break;}}System.out.println("程序一退出");}
}//定义一个ArrayStack表示栈class ArrayStack {private int maxSize;//栈大小private int[] stack;//数组模拟栈，数据放在数组private int top = -1;//栈顶//构造器public ArrayStack(int maxSize) {this.maxSize = maxSize;stack = new int[this.maxSize];}//判断是否栈满public boolean isFull() {return top == maxSize-1;}//判断是否栈空public boolean isEmpty() {return top == -1;}//入栈public void push(int value) {if (isFull()) {System.out.println("栈满");return;}top++;stack[top] = value;}//出栈public int pop() {if (isEmpty()) {throw new RuntimeException("栈空");}int value = stack[top];top--;return value;}//显示栈public void list() {if (isEmpty()) {System.out.println("栈空");return;}for (int i = top; i >= 0; i--) {System.out.printf("stack[%d]=%d\n", i, stack[i]);}}}

3 用链表实现栈
1）用链表实现栈的思路分析
入栈：相当于新new一个头结点，然后让新节点指向单链表的头结点
出栈：只要将链表的头指针后移到它的next，将next作为新的头结点
2）代码实现

public class LinkedListStackDemo {public static void main(String[] args) {Node node1 = new Node(1, "貂蝉");Node node2 = new Node(2, "西施");Node node3 = new Node(3, "王昭君");Node node4 = new Node(4, "杨玉环");Stack stack = new Stack();stack.push(node1);stack.push(node2);stack.push(node3);stack.push(node4);for(int i=0;i<4;i++){Node popNode = stack.pop();System.out.println(popNode);}}
}//栈
class Stack{private Node head = new Node(0,"");//入栈public void push(Node newNode){//创建辅助指针Node temp = head;//栈为空时if(temp.next == null){temp.next = newNode;}else{newNode.next = temp.next;temp.next = newNode;}}//出栈public Node pop(){//栈空if(head.next == null){//抛出异常结束方法throw new RuntimeException("栈空，不能取数据");}//创建辅助指针Node temp = head;if(temp.next.next != null){Node popNode = temp.next;temp.next = temp.next.next;return popNode;}else{return temp.next;}}
}//节点类
class Node{public int no;public String name;public Node next;public Node(int no,String name){this.no = no;this.name = name;}@Overridepublic String toString() {return "Node [no=" + no + ", name=" + name + "]";}}