2. 两数相加
class Solution {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
ListNode curr = new ListNode(0);
ListNode head = curr;
int plus =0;
while (l1 != null || l2!=null || plus !=0){
int a = l1==null?0:l1.val;
int b = l2==null?0:l2.val;
int res = (a + b + plus)%10;
plus = (a+ b +plus)/10;
curr.next = new ListNode(res);
curr = curr.next;
if(l1 != null) l1 = l1.next;
if(l2 != null) l2 = l2.next;
}
return head.next;
}
}