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;
        }
};