They have conducted a total of 4 rounds of interviews. The interview level is high, as they expect candidates to be up-to-date with modern tools.

The interviewers are very rude people. They discourage candidates. If a candidate doesn't match your expectations, you should simply let them go.

They will hold you for a large number of interview rounds. Also, they will comment rudely on your face if you don't meet their interview standards.

I attended an interview at another similar company. The situation was the same there, but they didn't discourage me; instead, they motivated me, stating it should be a good experience. That's the mark of a good interviewer.

Substrings question, linked lists.