Which are the easiest and toughest courses in the history of IIIT-Delhi?

I am an alumnus of B.Tech CSE from IIIT Delhi. I joined in 2008. These were the two most difficult courses in CSE during my time-

Only 2008 and 2009 batch students got to study under Khushil Saini. He taught Digital Circuits to first-semester students, and Computer Organization to second-semester students. Sir taught at NSUT before joining IIIT Delhi. 12 was the most one could score in Computer Organization, to pass with a D grade. However, some students did manage to score mid-twenties and get a B grade in both faculty subjects. Lab practicals were their saving grace. 

But while his marking scheme was so frightening, sir was a very polite person. He addressed us as a friend and was not threatening at all. Then there was the Theory of Computation taught by Dr. Astrid Kiehn. From a class of 60, 26 of us failed his course.

In spite of every hardship, I miss IIIT Delhi since graduating from this college.