1 class Solution {
 2     public:
 3         ListNode* reverse(ListNode* root)
 4         {
 5             if(NULL == root)
 6                 return NULL;
 7             ListNode* pCur = root;
 8             ListNode* pNext = root->next;
 9
10             while(pNext)
11             {
12                 pNext = pNext->next;
13                 pCur->next->next = pCur;
14                 pCur = pCur->next;
15             }
16             root->next = NULL;
17             return pCur;
18         }
19
20 };

ListNode * reverseList(ListNode* head)
{if(head == NULL) return NULL;ListNode *pre = NULL;ListNode *cur = head;ListNode *next = NULL;while(cur){next = cur->next;cur->next = pre;pre = cur;cur = next;}return pre;}

/*** Definition for singly-linked list.* struct ListNode {*     int val;*     ListNode *next;*     ListNode(int x) : val(x), next(NULL) {}* };*/
class Solution {
public:ListNode *addTwoNumbers(ListNode *l1, ListNode *l2){if(l1 == NULL)return l2;if(l2 == NULL)return l1;ListNode* p1 = l1;ListNode* p2 = l2;ListNode dummy(-1);ListNode* pNew = &dummy;int carry = 0;int sum = 0;while(p1 && p2){sum = (p1->val + p2->val + carry)%10;carry= (p1->val + p2->val + carry)/10;pNew->next = new ListNode(sum);pNew = pNew->next;p1 = p1->next;p2 = p2->next;}while(p1){sum = (p1->val +  carry)%10;carry= (p1->val + carry)/10;pNew->next = new ListNode(sum);pNew = pNew->next;p1 = p1->next;}while(p2){sum = (p2->val +  carry)%10;carry= (p2->val + carry)/10;pNew->next = new ListNode(sum);pNew = pNew->next;p2 = p2->next;}if(carry){pNew->next = new ListNode(carry);pNew = pNew->next;} return dummy.next;}};