either would work. I only suggested using bool since it keeps it simple.

For C#, the function type Boolean requires using System;
I suggest you just change it to bool.

is it just me, or is there something wrong with this test case???
(I did pass the sample test cases)

//Console.Write()
array = 1 1 1 3 1 3 2 3 2 1
final array = 1 1 1 3 3 2 3 2

//Test case output
([1,1,1,1,1,2,2,3,3,3], 3)

• Expected: 1,1,1,2,2,3,3,3 Actual: 1,1,1,3,3,2,3,2

there's a mistake in the test case. you forgot to put types().

The instructions should be a little more clear.
Also, you should mention when there are no braches, that the Description() output is different.

You should have a test case example for each output.

In C#, the input is always a string. Which means that there will be type casting. I think you should clarify that.