4.md

Ceil in BST

int ans=-1;

    int find(Node* root, int input)
    {
        if (root == NULL) return ans;
    
        if(root->data==input)   return ans=input;
    
        if(root->data > input)
        {
            ans=root->data;
            return find(root->left,input);
        }
        else
            return find(root->right,input);
    }
int findCeil(Node* root, int input) {
   
        find(root,input);
        return ans;
}