If you change tests in a way which makes existing solutions not pass anymore, then such solutions will be marked as obsolete. However, users who submitted them will not lose any points. It is generally OK to add tests and invalidate some solutions if tests are incorrect and do not conform to spec.

-- Java version of the kata --

The kata details state that inputs are not sorted. My tests have shown that at least one of the successfully submitted solutions is not correct.
This would be detected if a test was added for the following input (expected result: 3):
new int[][] {{10, 11}, {1, 8}, {6, 9}, {5, 7}})

I have a general question (sorry if it is not an appropriate forum, I am new here)

• Adding sort to existing solutions will make them correct, but also will affect performance, so some of them might no longer be viable... Would a new test somehow invalidate solutions that are already submitted?

I think it's best to raise an issue for this kata. I have so many questions! see what happens :)

I really love the simplicity of this solution.
However - I tested it with this input: new int[][] {{10, 11}, {1, 8}, {6, 9}, {5, 7}})
and it returns 4 - note {10, 11} does not overlap with any other request - the result should be 3.

Am I missing something?