//My Code School solution public bool IsBST(BSTNode <int> root) => IsBSTUtil(root, int.MinValue, int.MaxValue);
public void AddNodeRecursive(int x)
{
var refNode = Root;
Root = AddNode(x, refNode);
}
public bool IsBinarySearchTree(BSTNode <int> root)
{
int _value = int.MinValue;
return(IsBST(root, ref _value));
}