What can I do in last 3 months to build a strong college application? suggest some colleges for cs in US and tip me.

Your SAT is competitive for all universities, including the Ivies, MIT, Stanford, etc. Your GPA seems rather low, but that may just be a peculiarity of the process you've chosen to convert your GPA to the American system. If you're top 2% in your school, that's good. It would fundamentally make you competitive for all universities. Grades don't get you into good US universities, though, your co-curriculars and overall profile do.

It is concerning that you're asking how to build a better profile three months before applications are due. There is literally is no way to build a competitive co-curricular profile for US universities in 3 months if you have not already engaged in all of your key experiences already. Unless you qualify for the IMO or something before applications are due, your current portfolio of co-curriculars will be the one you're gonna apply to universities with. Key experiences just take time; there's, pretty much by definition, no way to "speedrun" them.

If you have just held leadership positions within your high school with no significant, unique experiences made outside of your scholastic environment, I'd pretty much give up on the top 20 universities in the US, again, assuming you're not an IMO/IPhO/IChO/... participant or have an achievement which is equivalently impressive.

I don't think I can give you a good silver lining in terms of your chances of getting into a US T20 as an undergraduate in 2023 at least from what I'm seeing here, but you may have a good portfolio for a university in the UK, if you're interested. They have an admissions system that values grades quite a lot. If you still want to study abroad, Hong Kong and Singapore may be options worth looking into. And don't forget, you can always work hard as an undergrad and then get into a good US graduate school.

I recognize I'm being a bit harsh here, but I think you deserve to have a realistic outlook on your chances of getting into a T20 university. Just remember that I'm only trying to give you well-intentioned advice to the best of my knowledge.

Google "common data set" for each of the colleges you wish to attend. It will tell you what they consider most important in their applications.

I wish there was some magic formula for an application but sadly there isnt. Thus most of the schools you listed have a single digit acceptance rate.

Also google colleges that award the most full aid to international students. Good luck.

Your profile needs to be competitive to be accepted in the IVY league schools, like Carnegie, Cornell, etc. You need to take good extracurricular activities like sports, olympiads(private ones will also help), work(paid), etc. Try to attend good programs like Google for startups(if you are interested in entrepreneurship) or out-of-box thinking by IIT Madras etc, though all the registrations of these are closed now. Try to find others don't lose hope. Talking about the SAT score, you are in the top 1% congratulations and the GPA is also good. Do you have any volunteer experiences or some good leadership experiences like winning a debate or your team has won a sports competition through your strategy etc? If yes, you can apply.

If you want my suggestion (I am also an Indian), you apply to schools that have good acceptance rates like GSU, Purdue, Wisconsin-Madison, UIUC, etc. I have planned to apply in these 4 and some others. I will try to pursue my MS in the Ivy League colleges

Hope this helps bro.

Thanks and Signing off