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…

AddLinkedList.java

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

    ListNode help1 = l1, help2 = l2, dummyHead = new ListNode(0), help3 = dummyHead;
    int c = 0;
    while(help1 != null || help2 != null) {
        int a = help1 == null ? 0 : help1.val;
        int b = help2 == null ? 0 : help2.val;
        int sum = a + b + c;

        help3.next = new ListNode(sum % 10);
        c = sum / 10;

        help1 = help1 == null ? help1: help1.next;
        help2 = help2 == null ? help2: help2.next;
        help3 = help3.next;
    }

    if(c != 0)
        help3.next = new ListNode(c);

    return dummyHead.next;
}