Following is the pattern of CTS selection:
For CTS you will first face an aptitude test of 60 mins having 40 questions.Correct answer carry one mark and wrong answer carry 0.25 marks. Do prepare well for this test as this is where the main competition is. study general aptitude, some basic geometry, logical reasoning, time & distance etc.
Questions were from :Quantative (ratio & proportion, inequalities, quadratic etc)-Aptitude (puzzles)- English (para followed by deductions, filling blanks with correct words).
TIPS - Practice quantative and puzzles. Refer- R.S.Agarwal, CAT material
next you will be called for a technical interview. the interview is not so difficult if your technical is good. they ask very basic technical questions, and you will clear it very easily if your basic concepts are clear. my interview lasted for 20 mins. questions on Data structures, networks, C (he also asked me to write a small program). answer confidently and clearly say if you dont know the answer.
If you clear you will be called for HR interview. the interview is very easy but you should prepare for some typical questions like: