题目1: 两数相加
class Solution {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
ListNode pre = new ListNode(0);
ListNode cur = pre;
int c = 0;//表示进位
while(l1 != null || l2 != null){
int x = l1 == null ? 0 : l1.val;
int y = l2 == null ? 0 : l2.val;
int sum = x + y + c;
c = sum / 10;
sum = sum % 10;
cur.next = new ListNode(sum);
cur = cur.next;
if(l1 != null){
l1 = l1.next;
}
if(l2 != null){
l2 = l2.next;
}
}
if(c == 1){
cur.next = new ListNode(c);
}
return pre.next;
}
}