2.Add Two Numbers

python code:

class Solution(object):
    def addTwoNumbers(self, l1, l2):
        len1=0
        len2=0
        p=l1
        while p != None :
            p=p.next
            len1=len1+1
        p=l2
        while p != None :
            p=p.next
            len2=len2+1
        if (len1>=len2):
            p1=l1
            p2=l2
        else:
            p1=l2
            p2=l1
        result= ListNode(None)
        p=result
        addone=0
        while p2!=None:
            p.next= ListNode((p1.val+p2.val+addone)%10)
            addone=(p1.val+p2.val+addone)/10
            p=p.next
            p1=p1.next
            p2=p2.next
        while p1!=None:
            p.next= ListNode((p1.val+addone)%10)
            addone=(p1.val+addone)/10
            p=p.next
            p1=p1.next
        if(addone>0): 
            p.next= ListNode(addone)
        return result.next