[数据结构]什么是链表?

链表是一种物理存储单元上非连续、非顺序的存储结构，数据元素的逻辑顺序是通过链表中的指针链接次序实现的–百度百科

大致分为单链表和双向链表
1.单链表:每个节点包含两部分,一部分存放数据变量的data,另一部分是指向下一节点的next指针
2.双向链表:除了包含单链表的部分,还增加的pre前一个节点的指针

链表的优点在于,不需要连续的存储单元,修改链表的复杂度为O(1) (在不考虑查找时)
但是缺点也很明显:无法直接找到指定节点,只能从头节点一步一步寻找复杂度为O(n)

下面是自己实现的链表操作

public class MyNode {
    private Node headNode;
    private Node lastNode;
    private int size;

    public void insert(int index , int data) {
        if (index < 0 || index > size) {
            throw new IndexOutOfBoundsException();
        }
        Node node = new Node(data);
        if (0 == size) {
            headNode = node;
            lastNode = node;
        }else if (0 == index) {
            //头节点插入
            node.next = headNode;
            headNode = node;
        }else if (size == index) {
            //尾节点插入
            lastNode.next = node;
            lastNode = node;
        }else {
            Node preNode = get(index-1);
            Node nextNode = preNode.next;
            preNode.next = node;
            node.next = nextNode;
        }
        size++;
    }
    public Node get(int index) {
        if (index < 0 || index >= size) {
            throw new IndexOutOfBoundsException();
        }
        Node temp = headNode;
        for (int i = 0;i < index; i++) {
            temp = temp.next;
        }
        return temp;
    }

    public Node delete(int index) {
        if (index < 0 || index >= size) {
            throw new IndexOutOfBoundsException();
        }
        Node deleteNode = null;
        if (0 == index) {
            //删除头结点
            deleteNode = headNode;
            headNode = headNode;
        }else if (index == size - 1) {
            //删除尾节点
            Node preNode = get(index - 1);
            deleteNode = lastNode;
            preNode.next = null;
            lastNode = preNode;
        }else {
            Node preNode = get(index - 1);
            deleteNode = preNode.next;
            preNode.next = preNode.next.next;
        }
        size--;
        return deleteNode;
    }

    public void outPut() {
        Node temp = headNode;
        while (null != temp) {
            System.out.println(temp.data);
            temp = temp.next;
        }
    }

    public static void main(String[] args) {
        MyNode myNode = new MyNode();
        myNode.insert(0,1);
        myNode.insert(1,2);
        myNode.insert(2,3);
        myNode.insert(3,4);
        myNode.insert(4,5);
        myNode.delete(2);
        myNode.outPut();
    }
}