public static void main(String args[]) {
        BinaryTree bt = new BinaryTree();
        Node head = null;
        head = bt.addNode(10, head);
        head = bt.addNode(15, head);
        head = bt.addNode(5, head);
        head = bt.addNode(7, head);
        head = bt.addNode(19, head);
        head = bt.addNode(20, head);
        head = bt.addNode(-1, head);
        head = bt.addNode(21, head);
        head = bt.addNode(-6, head);
        CousinNodes cn = new CousinNodes();
        System.out.println(cn.areCousins(head, 10, 19));
        System.out.println(cn.areCousins(head, 19, 7));
        System.out.println(cn.areCousins(head, 19, -1));
        System.out.println(cn.areCousins(head, 19, -6));
        System.out.println(cn.areCousins(head, -1, 7));
        System.out.println(cn.areCousins(head, 7, -1));
    }
Little more efficient than other method since this guy does not need
another look up to see if parent is same for found nodes.
src/com/interview/tree/CousinNodes.java