BCS, Bachelor of Computer science is a three year program with the core being computer studies. The eligibility would be 50% in 12 th standard with the core group being physics, chemistry and mathematics.There would be an basic entrance exam that decided on the enrollment. You need to write the common state level entrance exams, KCET in Karnataka, UPSEE in Uttar Pradesh, TANCET in Tamil Nadu and so on.
Just my suggestion, you can think about it.
What are your career aims? Why have you chosen Bachelor of Computer science?
If you have the time a B.Tech or a BE in computer science, this is one year more but would give you a better grasp of the subject and fundamentals. It would also give you an engineering degree after which you can take on GATE and similar exams and be eligible for a better paid job or even pursue your Masters and be update with your qualifications for the job market.