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* nhead=NULL;
        ListNode* current=head;
        while(current!=NULL){
            ListNode* tmp=current;
            current=current->next;
            tmp->next=nhead;
            nhead=tmp;
        }
        return nhead;
        
        
    }
};