12/9
注意一下循环终止条件不光是遍历到两个链表尾部,还要进位为0
class Solution {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
ListNode bef = new ListNode();
ListNode head = bef;
int flag = 0;
int nowval;
while (true) {
if (l1 == null && l2 == null) {
if (flag == 0) {
break;
} else {
nowval = flag;
}
} else if (l1 == null) {
nowval = l2.val + flag;
l2 = l2.next;
} else if (l2 == null) {
nowval = l1.val + flag;
l1 = l1.next;
} else {
nowval = l1.val + l2.val + flag;
l1 = l1.next;
l2 = l2.next;
}
flag = nowval / 10;
bef.next = new ListNode(nowval % 10);
bef = bef.next;
}
return head.next;
}
}