/* Examines the binary tree rooted at |node|. Zeroes |*okay| if an error occurs. Otherwise, does not modify |*okay|. Sets |*count| to the number of nodes in that tree, including |node| itself if |node != NULL|. All the nodes in the tree are verified to be at least |min| but no greater than |max|. */ static void recurse_verify_tree (struct bst_node *node, int *okay, size_t *count, int min, int max) { int d; /* Value of this node's data. */ size_t subcount[2]; /* Number of nodes in subtrees. */ if (node == NULL) { *count = 0; return; } d = *(int *) node->bst_data; if (min > max) { printf (" Parents of node %d constrain it to empty range %d...%d.\n", d, min, max); *okay = 0; } else if (d < min || d > max) { printf (" Node %d is not in range %d...%d implied by its parents.\n", d, min, max); *okay = 0; } recurse_verify_tree (node->bst_link[0], okay, &subcount[0], min, d - 1); recurse_verify_tree (node->bst_link[1], okay, &subcount[1], d + 1, max); *count = 1 + subcount[0] + subcount[1]; }