leetcode --- Reverse Linked List

Reverse a singly linked list.
单链表的反转。

解题思路：
指针移位，相邻的互换。

class Solution {
public:
    ListNode* reverseList(ListNode* head) {
        ListNode *pre=NULL, *curr, *next;  //三个结点
        curr = head;//从头结点开始
        while (curr)
        {
            next = curr->next; //把当前点的下一个点保存起来
            curr->next = pre;//相邻的互换
            pre = curr;     //指针移位
            curr = next;
        }
        return pre;
    }
};