# 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):
"""
:type l1: ListNode
:type l2: ListNode
:rtype: ListNode
"""
#会有进位，求进位用相加的和对10取整求出来的是进位的值，对10取余是留在当前位的,
if l1==None:
return l2
if l2==None:
return l1
dummy=ListNode(0)
p=dummy
carry=0
while l1 and l2 :
p.next=ListNode((l1.val+l2.val+carry)%10)
carry=(l1.val+l2.val+carry)//10
l1=l1.next
l2=l2.next
p=p.next
if l1:
while l1:
p.next=ListNode((l1.val+carry)%10)
carry=(l1.val+carry)//10
l1=l1.next
p=p.next
if l2:
while l2:
p.next=ListNode((l2.val+carry)%10)
carry=(l2.val+carry)//10
l2=l2.next
p=p.next
if carry==1:
p.next=ListNode(1)
return dummy.next
