User solved it (I copied View Solution code and started debugging, but passed Attempt on first try) but didn't bother to close Question afterwards -.-

No problems with Python tests therefore & closing Question.

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In case of in it depends on data structure. Hashmap based set and dict don't iterate items (unless everything has the same hash which is extremely unlikely), but list and tuple do.

Either author should specify that blatant for shouldn't be used or add tests accodringly to your' suggestion.

If you don't mind some random drive-by feedback on your code:

Your solution is a prime example of violating the DRY principle. It is 4 times longer than it needs to be. Seeing your kyu level I'm not sure whether you might be doing this on purpose, so disregard if none of this is news to you :)

Specifically, this is regarding the way you do multiple comparisons on the value of d. In the context, d will always be exactly one and only one of the four options R U D L. Inside every if-block, the code is pretty much identical, except for minor details. A way of avoiding repetition, and thus increasing legibility and comprehensibility, would be to bundle up the dependecies (values of d) together with the changes they imply. A dict is perfectly suited for this. There is also always the performance aspect to consider: boolean checks may be fast, but they are not free. Every step, you are performing 4 conditional checks. You can reduce this down to 0. Checking whether the head is out-of-bounds doesn't have to be tailored individually to each value of d. There is one valid condition for b and one valid condition for a, irrespective of d.

No(

it is nice to be surprised after submit my code and see a much better solution :)

No problem. Thank you!

Python translation should be fixed, thanks for posting this.

I'm sorry I haven't been on codewars in years. Just found the tab people have been referring to and should be fixed.

I'm sorry I haven't been on codewars in years. Just found the tab people have been referring to and should be fixed.

Sample tests in Python are still wrong.

It is still the same in the sample tests!