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

int x=0, y=0, carry=0, sum=0;

ListNode *h=NULL, **t=&h;

while (l1!=NULL || l2!=NULL){

x = getValueAndMoveNext(l1);

y = getValueAndMoveNext(l2);

sum = carry + x + y;

ListNode *node = new ListNode(sum%10);

*t = node;

t = (&node->next);

carry = sum/10;

}

if (carry > 0) {

ListNode *node = new ListNode(carry%10);

*t = node;

}

return h;

}

int getValueAndMoveNext(ListNode* &l){

int x = 0;

if (l != NULL){

x = l->val;

l = l->next;

}

return x;

}