Cracking the Coding Interview is a good way to prepare

The problems on Facebook, Microsoft and Google are usually Div2 A and B (hardly C) problems, but sometimes they ask about graphs, tries, and other data structures (that are never present on Div2 ABC).

Nikita_Babenko linked a very good reference to prepare (Cracking the Coding Interview) (don't ignore the first chapters. Explaining your experience listed on your resume is a must on some interviews).

Also https://leetcode.com/ is good to practice for problems since it have problems using on real interviews.

Another thing is mock interviews. If you have teammates, or friends doing the interviews, practice interviewing them. Explaining the solution clearly is what you have to do during interviews. Some problems can be hard (or we tend to be very nervous and don't see the easy way), so try to explain your thoughts. The interviewers usually want to know if you can solve the problems fast, but if you can't they want to know if you can get to the answer with some help. It's natural to not know everything.

Codeforces is not so good of a reference, but solving problems anywhere helps.

And good luck!

I've done interviews with Facebook.
I just have a quick tip to add to naumazeredo's great answer,

Be careful with details (such as ambiguity, corner cases, coding style... etc.).
naumazeredo is right about the difficulty of these questions.
However, interview questions are often asked with hidden ambiguities. This might include the size of input, range of numbers, permissible conditions (eg. can a number be used twice?) ...etc..
It's also very likely that these questions will include sneaky corner cases you need to think of before coding. You don't want to write an ugly fix for just one type of corner case.
As for coding style, the interviewers at these big-4 companies will seriously look for signals that indicate whether you're a good developer. So if you're one of those people who use a, b, c as variable names for example, quit doing so during interviews.

naumazeredo suggested LeetCode. It's a great source, but I want to add somthing, check out this npm cli for leetcode (https://github.com/skygragon/leetcode-cli-plugins). It has plugins, one of them is called 'company' (basically you can filter the problems by the company they were asked). Running smthng like leetcode list -t facebook will give you all the problems asked previously by facebook. If you have money I suggest buying premium for leetcode of course :) Btw, the company tags are for real, those are real problems from interviews, I encountered 3 of them at Palantir and Google.

Good luck

:thinking:

I did an interview for Facebook, but the role was actually more like support for their gaming API. I failed the only question I was given: "How can Facebook compete with Steam on PC gaming market?" :)

Is CGPA very important to get interview offer in facebook? Is it possible to select for interview in facebook with good coding skill and bad CGPA?

Inteviewbit is a good place to practice questions for interview. It's similar to leetcode.

I_love_Tanya_Romanova might be able to guide you

Also, do the big 4 consider students with non-cs and non-electrical undergrad degree to at least give the online test/telephonic round? Do you know of anyone here from non-CS who got a chance to give the interview ?