find min in binary tree.recursive.cpp

struct BstNode
{
    int data;
    BstNode *left;
    BstNode *right;
};

int FindMin(BstNode *root)
{
    if (root == NULL)
    {
        cout << "Error: Tree is empty\n";
        return -1;
    }
    else if (root->left == NULL)
    {
        return root->data;
    }
    // Search in left subtree.
    return FindMin(root->left);
}