LeetCode-206. Reverse Linked List

/**
* Definition for singly-linked list.
* struct ListNode {
*     int val;
*     ListNode *next;
*     ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode* reverseList(ListNode* head) {
if(head == NULL || head->next == NULL)  return head;
ListNode Result(0);
ListNode *p = head;
while (p) {
ListNode *q = p->next;
p->next = Result.next;
Result.next = p;
p = q;
}
return Result.next;
}
};