/* Generates a list of integers that produce a balanced tree when
   inserted in order into a binary tree in the usual way.
   |min| and |max| inclusively bound the values to be inserted.
   Output is deposited starting at |*array|. */
static void
gen_balanced_tree (int min, int max, int **array)
{
  int i;

  if (min > max)
    return;

  i = (min + max + 1) / 2;
  *(*array)++ = i;
  gen_balanced_tree (min, i - 1, array);
  gen_balanced_tree (i + 1, max, array);
}