getIntersectionNode = function (headA, headB) {
    let a = headA;
    let b = headB;
    while (a !== b) {
        a = a === null ? headB : a.next;
        b = b === null ? headA : b.next;
    }

    return a;
}
@param {ListNode} headA
@param {ListNode} headB
@return {ListNode}