/*

public class ListNode {

int val;

ListNode next = null;

ListNode(int val) {

this.val = val;

}

}*/

public class Plus {

public ListNode plusAB(ListNode a, ListNode b) {

// write code here

if(a == null || b == null){

return null;

}

int add = 0;

ListNode head = new ListNode(-1);

ListNode resCur = head;

ListNode curA = a;

ListNode curB = b;

while(curA != null || curB != null){

if(curA != null && curB !=null){

resCur.next = new ListNode((curA.val+curB.val+add)%10);

resCur = resCur.next;

add = (curA.val+curB.val+add)/10;

curA = curA.next;

curB = curB.next;

}else if(curA != null){

resCur.next = new ListNode((curA.val+add)%10);

resCur = resCur.next;

add = (curA.val+add)/10;

curA = curA.next;

}else{

resCur.next = new ListNode((curB.val+add)%10);

resCur = resCur.next;

add = (curB.val+add)/10;

curB = curB.next;

}

}

if(add > 0){

resCur.next = new ListNode(add);

resCur = resCur.next;

}

return head.next;

}

}