This is most easy problem in last list on
euler angles and optimization.
But I tried 30 submissions on test 2 because
taken columns of optimal rotation matrix
but should take rows acording of nature of dual basis.

I really appreciate that you help people solving hard problems )))

Now a few questions about your post.
Is your solution complexity O(n^4) ?
And do you mean one should output the tranposed rotation
matrix (which is equal to the inverse matrix, because the
rotation matrix is orthogonal) ?

My post has emotional nature only .
I saw that only 1 solved 1672 and thought that
problem really hard but it to appear of school level.
But what to use: rows or columns is rather
non evidence and your are all right about ortogonality.
Without ortogonality we must inverse matrix of transformation but for ortogonal case just transpose
is applicable.

My post has emotional nature only .
I saw that only 1 solved 1672 and thought that
problem really hard but it to appear of school level.
But what to use: rows or columns is rather
non evidence and your are all right about ortogonality.
Without ortogonality we must inverse matrix of transformation but for ortogonal case just transpose
is applicable.
P.S. My posts have also idea that all problems is
excersises only and don't have the value to
battle during years with.

I can't say that I spend too much time on some particular problems.
But it's interesting for me to solve all problems from this contest.
And it looks quite realistic thanks to your hints))