Hey !

The basic eligibility criteria for computer science engineering is 10+2 from a recognised board with physics ,chemistry and maths as main subjects with minimum aggregate score of 55% in PCM. So ,if you take PCM in 12 and score the minimum qualifying marks ,you are surely eligible for CSE. And after 12 , you have to appear for various exams such as JEE ,BITSAT ,VITEE etc to name a few. And on the basis of your performance , you will be allotted seat. For more details about CSE ,do follow the given link :

https://engineering.careers360.com/articles/computer-science-engineering-0

Hope it helps!