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 contains 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.
Example:
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4) Output: 7 -> 0 -> 8 Explanation: 342 + 465 = 807.
Solution
/** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int x) { val = x; } * } */ public class Question2Solution { public ListNode addTwoNumbers(ListNode l1, ListNode l2) { ListNode head = new ListNode(0); int carry = 0; ListNode currNode = head ; while (l1 != null || l2 != null) { int x1 = (l1 != null ? l1.val : 0); int x2 = (l2 != null ? l2.val : 0); int sum = x1 + x2 + carry; carry = sum / 10; currNode.next = new ListNode(sum % 10); currNode = currNode.next; if (l1 != null) l1 = l1.next; if (l2 != null) l2 = l2.next; } if (carry == 1) { currNode.next = new ListNode(carry); } return head.next; }