[leetcode] AddTwoNumbers

/**
*
* <pre>
* You are given two linked lists representing two non-negative numbers.
* 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.
*
* Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
* Output: 7 -> 0 -> 8
* </pre>
*/
public class AddTwoNumbers {

    public class ListNode {
        int      val;
        ListNode next;

        ListNode(int x) {
            val = x;
            next = null;
        }
    }

    public class Solution {
        public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
            if (l1 == null)
                return l2;
            if (l2 == null)
                return l1;

            int value = (l1.val + l2.val) % 10;
            int carry = (l1.val + l2.val) / 10;
            ListNode head = new ListNode(value);
            ListNode tail = head;
            l1 = l1.next;
            l2 = l2.next;
            while (!(l1 == null && l2 == null && carry == 0)) {
                int temValue = carry;
                if (l1 != null) {
                    temValue += l1.val;
                }
                if (l2 != null) {
                    temValue += l2.val;
                }
                value = (temValue) % 10;
                carry = (temValue) / 10;
                ListNode node = new ListNode(value);
                tail.next = node;
                tail = node;

                if (l1 != null) {
                    l1 = l1.next;
                }
                if (l2 != null) {
                    l2 = l2.next;
                }
            }

            return head;
        }
    }
}