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.