I am a firmware developer with 4 years experience. C and sometimes assembly is my bread and butter.

Like 2 years ago, I was really interested to make a switch to application development. Got referred by my friend to her startup.

But I was a bit rusty with my data structures, high level languages and interpersonal skills.

The first question was to find the number of occurences for each word in a paragraph. The language choice was Java. But I was allowed to use C++ since it was the closest relative to Java that I knew.

And I started implementing a binary search tree from scratch and started inserting each tokenised word into it, wrote a traversal algorithm.

The interviewer, luckily, was a patient guy. After I completed my whole mess, he asked is it possible to do this in a slightly better way with constant time access without traversal.

I said yes, we can with a hash table but I dont know how to implement one. He replied I dont expect you to implement the hash table but see you use it. I asked him if I am allowed to used the standard library, for which he said ofcourse.

*facepalm*.

Finally I understood his expectation, referred cppreference.com and used an unordered_map.

Later there were some quesion on databases for which I tried my best to answer. And I frankly replied that I am not comfortable with JS frameworks as of now. Got rejected.

So the mistake is I never asked basic questions like what is the time complexity expects, if I was allowed to use standard library, didnt spend some extra time on studying stuffs needed for the domain switch and most importantly I panicked.