02.两数相加

 1 class Solution {
 2     public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
 3         // 创建一个哑结点
 4         ListNode dummyNode = new ListNode(0);
 5         ListNode p = l1, q = l2, curr = dummyNode;
 6         int carry = 0;
 7         while(p != null || q != null){
 8             // 用x,y取出p,q的val值
 9             int x = (p!=null)? p.val : 0;
10             int y = (q!=null)? q.val : 0;
11             int sum = carry + x + y;
12             // 用numerical存放进位之后的值
13             int numerical = sum % 10;
14             curr.next = new ListNode(numerical);
15             // 将当前节点向下一个节点移动
16             curr = curr.next;
17             if(p != null)
18                 p = p.next;
19             if(q != null)
20                 q = q.next;
21             carry = sum / 10;
22         }
23         // 判断是否有进位
24         if(carry > 0)
25             curr.next = new ListNode(carry);
26         return dummyNode.next;
27     }
28 }