Code is not giving correct result

#1

input:-
1
10
1 2 3 4 5 6 7 8 9 10
please tell me how to debug this program?

#2

Just made little changes to it . Please check them if it is working correct now.

#include<iostream>
using namespace std;
class node{
	public:
	int data;
	node* left;
	node* right;
	node(int d)
	{
		data=d;
		left=nullptr;
		right=nullptr;
	}
};
node* buildBalancedBST(int a[],int i,int j)
{ 
    // cout<<i<<" "<<j<<endl;
	if(i==j)
	{
		return new node(a[i]);	
	}
	else if(i>j)
	return NULL;
	else
	{
		int mid=(i+j)/2;
		node* left=buildBalancedBST(a,i,mid-1);
		node* right=buildBalancedBST(a,mid+1,j);
		node* nd=new node(a[mid]);
		nd->left=left;
		nd->right=right;
		return nd;
	}
	// return nullptr;
}

void printPreorder(node* root)
{
	if(root)
	{
		cout<<root->data<<" ";
		printPreorder(root->left);
		printPreorder(root->right);
	}
}

int main() {
int t;
cin>>t;
while(t--)
{
	int a[10000];
	int n;
	cin>>n;
	for(int i=0;i<n;i++)
	cin>>a[i];
	node* root=buildBalancedBST(a,0,n-1);
	printPreorder(root);
}
}
#3

Its giving wrong answer