剑指Offer 24 反转链表

反转链表

输入一个链表，反转链表后，输出新链表的表头。

# -*- coding:utf-8 -*-
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
class Solution:
    # 返回ListNode
    def ReverseList(self, pHead):
        if pHead == None:
            return None
        head = pHead
        nextnode = pHead.next
        t = ListNode(0)
        while head:
            head.next = t.next
            t.next = head
            head = nextnode
            if nextnode != None:
                nextnode = nextnode.next
        return t.next
        # write code here

 

Java版，leetcode地址：

class Solution {
    public ListNode reverseList(ListNode head) {
        if (head == null) {
            return null;
        }
        if (head.next == null) {
            return head;
        }
        ListNode phead = head;
        ListNode nextNode = head.next;
        ListNode t = new ListNode(0);
        while (phead != null) {
            phead.next = t.next;
            t.next = phead;
            phead = nextNode;
            if (nextNode != null) {
                nextNode = nextNode.next;
            }
        }
        return t.next;
    }
}