Add Two Linked Lists

Given two Linked Lists that each represent a non-negative integer in in reverse (23 would be given as (3) -> (2)), write a method to add these numbers and return as the result as a linked list.

Example: given (3) -> (2) and (7) -> (2) as input, your method should return (0) -> (5) which is (23 + 27 = 50).

Solution

public static Node addTwoLL(Node list1, Node list2) {
    Node resultList = null;
    Node prev = null;
    int carry = 0;

    while (list1 != null || list2 != null || carry != 0) {
        Node curr = new Node();
        int sum = (list1 == null ? 0 : list1.val) + (list2 == null ? 0: list2.val) + carry;
        curr.val = sum % 10;
        carry = sum / 10;

        if (resultList == null) {
            resultList = curr;
        }
        else {
            prev.next = curr;
        }

        prev = curr;
        if(list1 != null) list1 = list1.next;
        if(list2 != null) list2 = list2.next;
    }

    return resultList;
}