I Didnt understand what is meant by when it says your solution is hacked

Its better to use Simple Binary search that would give you O(log n) time complexity in this the code can be :

int BinarySearch(int arr[],int x,int n)

{

int low=0; int high=n;

while(low<=high) {

int mid=low+(high-low)/2;

if(x<arr[low])

{
  return low;

  break;

}

if(x>=arr[high])

{

  return high+1;

  break;

}

if(x<arr[mid])
{
  high=mid-1;
}
else if(x>=arr[mid])
{
  low=mid+1;
}

} this will surely give you the time complexity you need