【剑指offer】反转链表

题目描述

输入一个链表，反转链表后，输出新链表的表头。

题解

/*
public class ListNode {
    int val;
    ListNode next = null;
 
    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {
    public ListNode ReverseList(ListNode head) {
        if(head == null)
            return null;
        ListNode newHead = head;
        ListNode nextNode = head.next;
        head.next = null;
        ListNode temp = null;
        while(nextNode != null) {
            temp = nextNode;
            nextNode = nextNode.next;
            temp.next = newHead;
            newHead = temp;
        }
        return newHead;
    }
}