#### QUESTION:

You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4) Output: 7 -> 0 -> 8

#### SOLUTION:

``````public class Solution {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
ListNode result  = new ListNode(0);
ListNode cur  = result;
int carry = 0;
while(l1 != null || l2!=null || carry!=0){
int a = 0, b = 0;
if (l1 != null) a = l1.val;
if (l2 != null) b = l2.val;
int value = (a+b+carry)%10;
carry = (a+b+carry)/10;
cur.val = value;
if((l1!=null && l1.next!=null) || (l2!=null && l2.next!=null)|| carry != 0){
ListNode next = new ListNode(0);
cur.next = next;
cur = cur.next;
}
if(l1!=null) l1=l1.next;
if(l2!=null) l2=l2.next;
}
return result;
}
}
``````
``````class Solution(object):
"""
:type l1: ListNode
:type l2: ListNode
:rtype: ListNode
"""
if l1==None and l2==None : return None
result = ListNode(0)
carry = 0
if(l1!=None or l2!=None):
if l1==None :
result.val = l2.val
elif l2==None :
result.val = l1.val
else :
result.val = (l1.val+l2.val + carry ) % 10
carry = (l1.val+l2.val+ carry)/10
while(l1.next!=None or l2.next!=None):
if (l1.next != None or l2.next != None):
result.next = ListNode(0)
if l1.next == None:
result.next.val = (l2.next.val +carry) %10
carry = (l2.next.val+carry)/10
elif l2.next == None:
result.next.val = (l1.next.val + carry) %10
carry = (l1.next.val+carry)/10
else:
result.next.val = (l1.next.val + l2.next.val + carry) % 10
carry = (l1.next.val + l2.next.val + carry) / 10
if l1.next != None: l1 = l1.next
if l2.next != None: l2 = l2.next
result = result.next
if carry!=0 : result.next = ListNode(1)