I don't think it works that way. You're also given an integer N which is greater than or equal to 2 and less than V.size(). You can reverse N contiguous items

I don't think it works that way. You're also given an integer N which is greater than or equal to 2 and less than V.size(). You can reverse N contiguous items in V at a time. So, you always revert the same number of elements in the vector. In your example, you revert 5 elements and then 4. Your example would give the following sequence: [1 2 3 4 5 6] [1 6 5 4 3 2] [3 4 5 6 1 2] [3 2 1 6 5 4] [5 6 1 2 3 4] [5 4 3 2 1 6] [1 2 3 4 5 6] For that case (6 elements and N=5), it looks like not many vectors V have a solution... but I'm too tired to keep going :)