2. 两数相加
比较简单的递推
1 class Solution { 2 public ListNode addTwoNumbers(ListNode l1, ListNode l2) { 3 ListNode l3 = new ListNode(),l4=l3; 4 int tag=0; 5 while(l1!=null || l2!=null){ 6 int val1 = l1==null ? 0:l1.val; 7 int val2 = l2==null ? 0:l2.val; 8 int temp = val1+val2+tag; 9 tag=temp/10; 10 temp=temp%10; 11 l3.next = new ListNode(temp); 12 l3=l3.next; 13 l1 = l1==null ? null:l1.next; 14 l2 = l2==null ? null:l2.next; 15 } 16 if(tag>0){ 17 l3.next = new ListNode(tag); 18 l3=l3.next; 19 } 20 return l4.next; 21 } 22 }