Dear aspirant,
According to your question there is no as such minimum percentile which would be required to take admission into NITS in these branches(mentioned by you).
Admission in these colleges are done on the basis of all india rank and so it is next to impossible to predict the minimum percentile required as the quality of students that appear for the exam changes every year.
But on a general basis a percentile of 97+ would be a safer score.
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