Taxi4Sure Interview Experience

I had attended taxi4sure drive. Their process is written test followed by n f2f interviews.

Written test
1) Given an array of students whose ranks can be 0 or 1. Sort the elements so that all the students with rank 0 come before 1.
Bonus points if algo is in-place
2) Find the first student from left side with rank 1
3) Write the algo to sort the students based on rank if the possible ranks are 0,1,2

I have given counting sort algo but looks they did not like my solution so was not proceeded further.