Count BST nodes that lie in a given range

Given a Binary Search Tree (BST) and a range l-h(inclusive), count the number of nodes in the BST that lie in the given range.

• The values smaller than root go to the left side
• The values greater and equal to the root go to the right side

• Time : O(n)
• Space : O(d)

int getCount(Node *root, int l, int h) {
    if(!root) return 0;
    int res = 0;
    if(l <= root->data and root->data <= h) {
        res = 1 + getCount(root->left, l, h) + getCount(root->right, l, h);
    } else if(l > root->data) {
        res = getCount(root->right, l, h);
    } else {
        res = getCount(root->left, l, h);
    }
    return res;
}