LeetCode 002 AddTwoNumbers

package ywheel.leetcode._002_add_two_numbers;

/**
* 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
*
* @author ywheel
*
*/
public class AddTwoNumbers {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
ListNode next = null;
ListNode head = null;
int decade = 0;
while (l1 != null || l2 != null || decade > 0) {
int l1_val = l1 == null ? 0 : l1.val;
int l2_val = l2 == null ? 0 : l2.val;
int sum = l1_val + l2_val + decade;
ListNode newNode = new ListNode(sum % 10);
decade = sum / 10;
if (next == null) {
next = newNode;
head = next;
} else {
next.next = newNode;
next = next.next;
}
l1 = l1 == null ? null : l1.next;
l2 = l2 == null ? null : l2.next;
}
return head;
}

public static void main(String[] args) {
AddTwoNumbers solution = new AddTwoNumbers();
// construct two inputs
ListNode l1 = new ListNode(2);
ListNode l11 = new ListNode(4);
ListNode l12 = new ListNode(3);
l1.next = l11;
l11.next = l12;
ListNode l2 = new ListNode(5);
ListNode l21 = new ListNode(6);
ListNode l22 = new ListNode(4);
l2.next = l21;
l21.next = l22;
ListNode resultNode = solution.addTwoNumbers(l1, l2);
if (resultNode != null) {
System.out.print(resultNode.val);
}
while (resultNode.next != null) {
resultNode = resultNode.next;
System.out.print("->" + resultNode.val);
}
}
}

/**
* Definition for singly-linked list.
*/
class ListNode {
int val;
ListNode next;

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