# 2 Add Two Numbers

Pseudocode:

ListNode ans = new ListNode(0)
while l1!=null && l2!=null 
    (l1+l2+carry) % 10, save the carry
    if(l1==null)
        concat rest of the node in l2
    if(l2==null)
        concat rest of the node in l1
if theres carry left, add a new listnode of carry

Code:

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {

        ListNode ans = new ListNode(0);
        ListNode ptr = ans;
        int carry = 0;
        while(l1!=null && l2!=null){
            int num = (l1.val+l2.val+carry) % 10;
            carry = (l1.val+l2.val+carry)/10;
            ptr.next = new ListNode(num);
            ptr = ptr.next;
            l1 = l1.next;
            l2 = l2.next;
        }
        while(l1!=null){
            ptr.next = new ListNode((l1.val+carry)%10);
            carry = (l1.val+carry)/10;
            ptr = ptr.next;
            l1 = l1.next;
        }
        while(l2!=null){
            ptr.next = new ListNode((l2.val+carry)%10);
            carry = (l2.val+carry)/10;
            ptr = ptr.next;
            l2 = l2.next;
        }
        if(carry!=0)
            ptr.next = new ListNode(carry);
        return ans.next;
    }
}