Interview Question for Software Engineer at Google:

public int binSer(int i, int j, int num, int[] arr){
    if (i > j){
        return -1;
    }
    int mid = (i+j)/2;
    if (arr[mid] == num){
        return mid;
    }
    if (arr[mid] < num{
        return binSer(mid+1,j,num,arr)
    }
    else {
        return binSer(i,mid,num,arr)
    }
}