剑指offer-16 链表反转

法一：

package Leetcode.ListNode;

/**
 * @Author: YCKJ3803
 * @Date: 2021/3/2 22:39
 * @Description: 反转链表，最经典的题，yyds！！！！
 */
public class ReverseListNode {
    private static class ListNode{
        int value;
        ListNode next;
    }
    private static ListNode reverseListNode(ListNode head){
        ListNode pre = null;
        ListNode p = head;
        while (p != null){
            ListNode next = p.next;
            p.next = pre;
            pre = p;
            p = next;
        }
        return pre;
    }
    private static void printListNode(ListNode head) {
        while (null != head) {
            System.out.print(head.value + "->");
            head = head.next;
        }
        System.out.println("null");
    }

    public static void main(String[] args) {
        ListNode root = new ListNode();
        root.value = 1;
        root.next = new ListNode();
        root.next.value = 2;
        root.next.next = new ListNode();
        root.next.next.value = 3;
        root.next.next.next = new  ListNode();
        root.next.next.next.value= 4;
        root.next.next.next.next = new ListNode();
        root.next.next.next.next.value = 5;
        printListNode(root);
        printListNode(reverseListNode(root));
    }

}

法二 

import java.util.Stack;

public class Test05<sout> {
    public static class ListNode{
        int Value;
        ListNode next;
    }
    //用栈
    public static void zhan(ListNode root){
        Stack<ListNode> stack = new Stack<>();
        while ( root != null){
            stack.push(root);
            root = root.next;
        }
        ListNode tmp;
        while (!stack.isEmpty()){
           tmp = stack.pop();
            System.out.println(tmp.Value+"");
        }
    }
    //用递归
    public static void Rucursion(ListNode root){
        if (root!=null){
            Rucursion(root.next);
            System.out.println(root.Value+"");
        }
    }
    public static void main(String[] args) {
        ListNode root = new ListNode();
        root.Value = 1;
        root.next = new ListNode();
        root.next.Value = 2;
        root.next.next =new ListNode();
        root.next.next.Value = 3;
        root.next.next.next = new ListNode();
        root.next.next.next.Value  = 4;
        root.next.next.next.next = new ListNode();
        root.next.next.next.next.Value  = 5;
//        zhan(root);
        Rucursion(root);
    }
}

参考文献

https://blog.csdn.net/guyuealian/article/details/51119499