Problem 5.2 -- tests fail with correct solution

My playground has no diff with the solution as shown here:

<img width="987" height="152" alt="Image" src="https://github.com/user-attachments/assets/814c7009-34fb-4438-bc37-6152faa3af00" />

But the tests still fail:

<img width="879" height="960" alt="Image" src="https://github.com/user-attachments/assets/9d3ffe52-36d6-4409-ab76-09819f7dca37" />