leetcode -- Algorithms -- 2_ Add two numbers

Solution 

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution(object):
    def addTwoNumbers(self, l1, l2):
        dummy = cur = ListNode(0)
        carry = 0
        while l1 or l2 or carry:
            if l1:
                carry += l1.val
                l1 = l1.next
            if l2:
                carry += l2.val
                l2 = l2.next
            cur.next = ListNode(carry%10)
            cur = cur.next
            carry //= 10
        
        return dummy.next

 oder mit recursive :

public:
    ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
        if(l1 == NULL) return l2;
        if(l2 == NULL) return l1;

        if(l1->val < l2->val) {
            l1->next = mergeTwoLists(l1->next, l2);
            return l1;
        } else {
            l2->next = mergeTwoLists(l2->next, l1);
            return l2;
        }
    }
};

而返回一个新的链表，只需要给指向第一个数据的指针地址就可以。 

Die analysis ist sehr gut. Finden Sie die Details mit den Link. 

https://leetcode.com/articles/add-two-numbers/