单双链表

单链表

定义

//单链表
public static class Node{
    public int value;
    public Node next;

    public Node(int data){
        value = data;
    }
}

单链表反转

新增1、2、3三个节点

public static Node reverseLinkedList(Node head){
    Node pre = null;
    Node next = null;
    while (head != null){
        //保存下next节点
        next = head.next;
        //头节点指针指向pre
        head.next = pre;
        //pre指向head节点
        pre = head;
        //head指向下一个节点
        head = next;
    }
    return pre;
}

双链表

定义

//双链表
public static class DoubleNode{
    public int value;
    public DoubleNode last;
    public DoubleNode next;

    public DoubleNode(int data){
        value = data;
    }
}

双向链表反转

新增1、2、3三个节点

public static DoubleNode reverseDoubleList(DoubleNode head){
    DoubleNode pre = null;
    DoubleNode next = null;
    while (head != null){
        //保存下next节点
        next = head.next;
        //头节点next指针指向pre
        head.next = pre;
        //头节点last指针指向next
        head.last = next;
        //pre指向head节点
        pre = head;
        //head指向下一个节点
        head = next;
    }
    return pre;
}