Function addTwoNumbers

javascript/0002-add-two-numbers.js:8–17

(l1, l2)

 * @return {ListNode}
 */
var addTwoNumbers = function (l1, l2) {
    let sentinel = (tail = new ListNode());

    return add(
        l1,
        l2,
        tail,
        sentinel,
    ); /* Time O(MAX(N, M)) | Space O(MAX(N, M)) */
};

const add = (l1, l2, tail, sentinel, carry = 0) => {
    const isBaseCase = !(l1 || l2 || carry);