剑指offer--22.反转链表

时间限制：1秒 空间限制：32768K 热度指数：440624

本题知识点： 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。

/*

struct ListNode {

    int val;

    struct ListNode *next;

    ListNode(int x) :

            val(x), next(NULL) {

    }

};*/

class Solution {

    public:

        ListNode* ReverseList(ListNode* pHead) {

            if(pHead == NULL) return NULL;

            ListNode* node = NULL,*pNext;

            pNext = pHead->next;//reserve

            pHead->next = NULL;    //断开

            node = pHead;//start

            pHead = pNext;

            while(pHead != NULL) {

                pNext = pHead->next;//reserve

                pHead->next = NULL;    //断开

                pHead->next = node;//反转

                node = pHead;

                pHead = pNext;//接着

            }

            return node;

        }

};