int val;

ListNode *next;

ListNode(int x) : val(x), next(NULL) {}

ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {

int len1 = getLen(l1), len2 = getLen(l2);

ListNode *p1 = len1 > len2 ? l1 : l2;

ListNode *p2 = len1 > len2 ? l2 : l1;

ListNode* pre = NULL;

int carried = 0;

while(p1){

int a = p1->val;

int b = p2 ? p2->val : 0;

p1->val = (a + b + carried) % 10;

carried = (a + b + carried) / 10;

pre = p1;

p1 = p1->next;

p2 = p2 ? p2->next : NULL;

}

pre->next = carried ? new ListNode(1) : NULL;

return len1 > len2 ? l1 : l2;

}

int getLen(ListNode* l){

int res = 0;

while(l)

res ++, l = l -> next;

return res;

}

return 0;

}