[LeetCode]Add Two Numbers

class Solution {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
    ListNode head=new ListNode(0),temp=head;
    int carry = 0;
    while (l1!=null||l2!=null) {
        int x=(l1!=null)?l1.val:0;
        int y=(l2!=null)?l2.val:0;
        int sum=x+y+carry;
        carry=sum/10;
        temp.next=new ListNode(sum%10);
        temp=temp.next;
        if (l1!=null) l1=l1.next;
        if (l2!=null) l2=l2.next;
    }
    if(carry>0)
        temp.next=new ListNode(carry);
    
    return head.next;
}
}