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
Code:
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
* @author liyiheng
*/
public class Solution {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
if (l1 == null && l2 == null) return null;
ListNode temp = l1 == null ? l2 : l1;
ListNode mayBeNull = l1 != null ? l2 : l1;
int value1 = l1 == null ? 0 : l1.val;
int value2 = l2 == null ? 0 : l2.val;
int extra = (value1 + value2) / 10;
temp.val = (value1 + value2) % 10;
if (extra > 0) {
if (temp.next != null) {
temp.next.val += extra;
} else {
temp.next = new ListNode(extra);
}
}
temp.next = addTwoNumbers(temp.next, mayBeNull == null ? null : mayBeNull.next);
return temp;
}
}