Add Two Numbers ，使用链表参数

# 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):
        l3 = ListNode(0)
        current = l3
        carry = 0
        while l1 or l2: # 1,1 | None,1 | 1,None
            # Pad 0 if None
            if l1 is None:
                l1v = 0
            else:
                l1v = l1.val
            if l2 is None:
                l2v = 0
            else:
                l2v = l2.val
            # Sum
            tmp = l1v + l2v + carry
            if tmp >= 10:
                x = tmp%10
                carry = int(tmp/10)
            else:
                x = tmp
                carry = 0
            # Assign value
            current.next = ListNode(x)
            current = current.next
            if l1 is not None:
                l1 = l1.next
            if l2 is not None:
                l2 = l2.next
        if carry != 0:
            current.next = ListNode(carry)
        return l3.next

node1=ListNode(1)
node2=ListNode(2)
node3=ListNode(3)

node1.next=node2
node2.next=node3

node4=ListNode(4)
node5=ListNode(5)
node6=ListNode(6)

node4.next=node5
node5.next=node6

x=Solution()
print(x.addTwoNumbers(node1,node4).val)
print(x.addTwoNumbers(node1,node4).next.val)
print(x.addTwoNumbers(node1,node4).next.next.val)

输出

5
7
9