class Solution {
public:
    ListNode* reverseList(ListNode* head) {
        ListNode * curr = head;
        ListNode * prev = NULL;
        ListNode * temp;

        while(curr != NULL){
            curr->next = prev;
            temp = prev;
            prev = curr;
            curr = curr->next;
            if(temp != NULL)
                temp->next = NULL;
        }
        return prev;
    }
};