力扣（LeetCode）官网 - 全球极客挚爱的技术成长平台
public ListNode addInList (ListNode head1, ListNode head2) {
// write code here
// 进行判空处理
if (head1 == null)
return head2;
if (head2 == null) {
return head1;
}
//先进行链表反转，再相加
ListNode h1 = reverse(head1);
ListNode h2 = reverse(head2);
//存放结果集
ListNode head = new ListNode(-1);
ListNode res = head;
int temp = 0;
while (h1 != null || h2 != null || temp > 0) {
if (h1 != null) {
temp = temp + h1.val;
h1 = h1.next;
}
if (h2 != null) {
temp = temp + h2.val;
h2 = h2.next;
}
res.next = new ListNode(temp % 10);
res = res.next;
temp = temp / 10;
}
return reverse( head.next);
}
public ListNode reverse(ListNode node) {
if (node == null) return node;
ListNode pre = null, next = null;
while (node != null) {
next = node.next;
node.next = pre;
pre = node;
node = next;
}
return pre;
}