Hi, for iiit hyd, there are two papers. 1st is aptitude paper. For this paper, i can refer to RS Agrawal. Dont go deep in it. But you should know how to approach to the different problems. There will be some questions based on 12th mathematics like 3d geometry, trigonometry. You should also prepare for that. And one more thing, this paper will also contain some C programming questions. Go through online c programming mcq sites, some good books for it.
Second paper will be based on core technical subjects. Just prepare like gate exam. That will be sufficient. I appeared last year for this exam and cracked it but couldnt crack intrview. Last yr most technical questions were asked from previous gate papers.
Hope this helps.