Hey Ramkrishna! Scoring 50% marks in JEE Advance is very good score which will eventually get you a seat in India's premium Institute for Engineering that is IITs. There are total 11k to 12k seats in IIT and by scoring that much marks you can get around 2k general rank which is very good to persue your favourite branch. 

50 percentage of marks is indeed a very good score in jee advance worthy of giving you admission in the top IITs.

If you get that much of marks then in general category your rank will be around 2 thousand and that in general category will be around 4 hundred, which is good enough to get you computer science in a top IIT.