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

# 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
        """
        rtype = ListNode(0)
        add=0
        r=rtype
        while l1 and l2:
            val = l1.val+l2.val+add
            if r.next:
                r=r.next
            r.val = val%10
            add = val/10
            l1=l1.next
            l2=l2.next
            r.next=ListNode(0)
            
        while l1:
            val = l1.val+add
            if r.next:
                r=r.next
            r.val = val%10
            add = val/10
            l1=l1.next
            r.next=ListNode(0)
            
        while l2:
            val = l2.val+add
            if r.next:
                r=r.next
            r.val = val%10
            add = val/10
            l2=l2.next
            r.next=ListNode(0)
        if add>0:
            r=r.next
            r.val=add
        r.next = None
        return rtype