int isNodeBST(p_node pn)
{
if (pn == NULL)
return 1;
if (pn->left != NULL && pn->left->value > pn->value)
return 0;
if (pn->right != NULL && pn->right->value < pn->value)
return 0;
if (!isNodeBST(pn->left) || !isNodeBST(pn->right))
return 0;
return 1;
}#include "bintree.h"
int isBST(t_tree t)
{
return isNodeBST(t.root);
}