IntersectionNode.java

private static ListNode getIntersectionNode(ListNode headA, ListNode headB) {
    
        if(headA == null || headB == null){
            return null;
        }
         
        final Set<ListNode> nodesA = new HashSet<>();
         
         ListNode currentA = headA;
         ListNode currentB = headB;
         
         while (currentA != null){
            nodesA.add(currentA);
            currentA = currentA.next;
         }
         
         while (currentB != null){
            if(nodesA.contains(currentB)){
                return currentB;
            }
            currentB = currentB.next;
         }
         return null;
}