delete()

/* Private delete() method */
private Node<Key, Value> delete(Node<Key, Value> x, Key key) {
    if (x == null) {                                                // 2
        return null;                                                // 2
    }

    int cmp = key.compareTo(x.key);                                 // 3
    if (cmp < 0) {                                                  // 4
        x.left = delete(x.left, key);                               // 4
    } else if (cmp > 0) {                                           // 5
        x.right = delete(x.right, key);                             // 5
    } else {                                                        // 6
        if (x.right == null) {                                      // 6
            return x.left;                                          // 6
        }
        if (x.left == null) {                                       // 7
            return x.right;                                         // 7
        }

        Node<Key, Value> t = x;                                     // 8
        x = findMin(t.right);                                       // 8
        x.right = deleteMin(t.right);                               // 8
        x.left = t.left;                                            // 8
    }
    x.size = 1 + size(x.left) + size(x.right);                      // 9
    return x;                                                       // 10
}