i got reference form the company employee then HR team asked me to come down to there office for the Interview process along with all relevant Documents and 5 passport photo

For a kick start with "Josh Technologies" You should have a good hold on data structures not only concepts but also the deep fundamental programming using link list,Bst, Output questions etc. also your fundas and applications for the concept must be clear and crystal. And the most important factor dealing with the complexities with respect to the code which is to be written must be perfect one. And if you have a good command in all of above. I am sure nobody can stop you to be there. All the best.