/**
 * 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) return head;
        ListNode *h = new ListNode(-1);

        ListNode *tail = head;
        while(tail != NULL)
        {
            tail = tail -> next;
            head -> next = h -> next;
            h -> next = head;
            head = tail;

        }
        return h-> next;
    }
};