I’ve solved the first Medium puzzle with both Python variants and I achieved 100% by means of the verification algorithm.
Though the third achievement (more than 50 links remaining) is not shown to be achieved although in testing interface I managed to get 52 links remaining. Multiple tests showed always the same result: 52. But after submitting the overview screen show completely different behavior and deletes way more links. Therefore I do not get the third achievement. Why is that?
The normal test cases and the validation test cases are similar, but not the same.
Your algorithm is the same in both tests, but the different input results in a different output. And in this case the output is not good enough to get the achievement.