What is the best material for gate preparation for CS?

you can find good study material at http://blog.oureducation.in/sample-paper-for-gate-cs-it/ and you can take online test at http://www.oureducation.in/itest

Lectures for GATE & PSUs Calculus Numerical Methods Linear Algebra Algorithms Video Lecture Databases - DBMS Video Lecture Computer Organization  Video Lecture Digital Logic Video Lecture Compiler Design Video Lecture Theory of Computation Video Lecture Discrete MATHEMATICS Video Lecture Set Theory & Algebra Mathematical Logic

OS:-Galvin DBMS:-Navathe/Korth Data Structures:-Tremblay and Sorenson Algorithms:-introduction to algorithms by Cormen (also contains basics on data structures)/ data structures and algorithms for GATE by Narasimha Karumanchi Theory of computation:-  Peter linz/Ullman Compiler design:- Ullman C programming:- let us c by yashwant kanetkar Computer networks:- Pieterson and Davie Discreet maths and graph theory :- Ralph Grimaldi / Narsinh Deo Solve the previous question papers

If i had to describe my preparation for GATE, i would do it in these three phases Phase 1: Understanding Topic Requirements for this phase are 1. Text books 2. Sample questions Textbooks that i referred were: 1. Digital Design, Morris Mano 2. Computer Organization, Hamacher 3. Operating Systems, Galvin 4. Database Management Systems, Korth 5. Computer Networks, Forouzan 6. Theory of Computer Science, Ullman 7. Compiler Construction, Ullman (Sethi one not Monica one) 8. Data Structures and Algorithms (Cormen) 9. C Programming (Dennis Ritchie) 10. Discrete Structures (Rosen) 11. Graph theory (Narshingh deo) 12. Linear Algebra (B S Grewal) 13. Permutation and Combination, Probability, Calculus //no specific textbook Note: Some of the textbooks have a lot of stuff which is irrelevant to GATE so ignore that part. You will get a sense of what is important after you start solving exam papers. And exam papers are the best source of sample questions. There is this wonderful website,  http://gateoverflow.in/questions with great explanation for difficult problems asked in GATE. You can refer it. Phase 2: Revision Requirements for this phase: 1. Some sort of Compendium 2. Bulk of questions I made my own compendium i.e. a list of small points that i thought were important in that topic. You may do the same or you can also refer http://www.ankurgupta.net/gate-notes/. They are good but i would still advice  you to make your own compendium. I didn’t solve many questions other that those which were previously asked in GATE and i think they were sufficient. What might additionally help is you can try to tweak previous GATE questions and solve them. It helps in gaining additional clarity in concepts. Again the best place for these questions is http://gateoverflow.in/questions Phase 3: Solving papers This phase is just as important as the previous two since you are dealing with a competitive exam here. You cannot escape giving tests. I joined test series of different classes but if you are looking for free alternatives i would suggest https://testbook.com/ and http://www.techtud.com/. I believe this material is sufficient for GATE CS.