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) {
ListNode* current,*pnext,*prev;
if(head == NULL || head->next == NULL)
return head;
current = head;
pnext = current->next;
current->next = NULL;
while(pnext){
prev = pnext->next;
pnext->next = current;
current = pnext;
pnext = prev;
}
head = current;
return head;
}
};