Tip 1:

One way to approach this problem is to start by looking at the simpler
following problem: given two equal-length sequences of notes a1 ... aC
and b1...bC do they match after transposition and re-order?

=========================================================================


Solution for Tip 1:

For that we find the following algorithm: sort both sequence and check
that the difference a_i-b_i is constant


=========================================================================

Tip 2 :

What is the complexity of a function taking a position p of the input and
checking whether input[p:p+C] is a ruminant seventh chord?




=========================================================================

Solution tip 2 :

We just apply the solution to tip 1. It is O(C×log(C)). Since C is small we
just need to repeat this for all positions.