#2

I am yet to solve this:

An array of size N has distinct values 1…N in random order. You have only operator called rev(X) (where X is any value from 0 to N-1) which reverses all values from 0 to X (example values 2,3,1,4 and rev(2) gets you 1,3,2,4). Our objective is to sort the array using minimum number of Rev(X) functions. How many permutations of N size array require exactly N number of rev(X) operators to get sorted?