leetcode2

/**

 * Definition for singly-linked list.

 * public class ListNode {

 *     public int val;

 *     public ListNode next;

 *     public ListNode(int x) { val = x; }

 * }

 */

public class Solution {

    public ListNode AddTwoNumbers(ListNode l1, ListNode l2) {

        var list = new List<ListNode>();

            var temp1 = l1;

            var temp2 = l2;

            var step = ;

            while (l1 != null || l2 != null)

            {

                var v1 = ;

                var v2 = ;

                if (l1 == null)

                {

                    l1 = new ListNode();

                }

                v1 = l1.val;

                l1 = l1.next;

                if (l2 == null)

                {

                    l2 = new ListNode();

                }

                v2 = l2.val;

                l2 = l2.next;

                var cur = v1 + v2 + step;

                var result = ;

                if (cur >= )

                {

                    step = ;

                    result = cur % ;

                }

                else

                {

                    step = ;

                    result = cur;

                }

                list.Add(new ListNode(result));

            }

            if (step == )

            {

                list.Add(new ListNode());

            }

            for (int i = ; i < list.Count - ; i++)

            {

                list[i].next = list[i + ];

            }

            var head = list[];

            return head;

    }

}

https://leetcode.com/problems/add-two-numbers/#/description

补充python实现：

 class Solution:

     def addTwoNumbers(self, l1: 'ListNode', l2: 'ListNode') -> 'ListNode':

         headnode = ListNode(0)

         temp = headnode

         carry = 0

         while  l1!=None or l2!=None:

             if l1==None:

                 l1 = ListNode(0)

             if l2==None:

                 l2 = ListNode(0)

             cur = l1.val + l2.val + carry

             if cur // 10 > 0:

                 carry = 1

             else:

                 carry = 0

             cur = cur % 10

             temp.next = ListNode(cur)

             temp = temp.next

             l1 = l1.next

             l2 = l2.next

         if carry > 0:

             temp.next = ListNode(carry)

         return headnode.next