My rank is 4lakh in IIT 2018....plz tell in which clgs I can get admission for CS.. .category Gen..plz don't say to use predictor

With a rank of 4 Lack i don't think you are going to get any good college and believe me "college does matter"!!!

Collegedoesmatter :
The original IITs, and BITs Pilani, are clearly better than other engineering colleges. Most NITs are better than most state engineering colleges (except the top state colleges). Top state colleges (e.g. COEP, VJTI, PICT) are clearly better than the second-tier engineering colleges. And so on. (Unfortunately, I dont really know how good or bad the new IITs are. Youll need to make that judgement on your own.)
Its fashionable to say the college doesnt matter. And it is very common to trot out examples of students from terrible colleges who have succeeded in life. But thats flawed logic. Students who succeed inspite of being in a bad college, are probably succeeding in spite of the college, not because of the college. And probably would have done even better if they had been in a better college.
Better colleges have better systems of education, better professors, and better resume value (which, whether you like it or not, is a factor for a long, long time.) Also, in better colleges, you have better classmates. This matters in the short term (because better classmates means more influence of friends who are interested in the right things), and the long term (better network)