void insert(int d) { TN p = new TN(d); if (root == null) root = p; else { TN nd = root, q = null; while (nd != null) { q = nd; if (d < nd.val) nd = nd.left; else nd = nd.right; } if (q.val > d) q.left = p; if (q.val <= d) q.right = p; } }