# [Community puzzle] Elevator

Has anyone got passed test 6?

The inputs for the test are 1999 1000 999 2 1, which seems like a result of IMPOSSIBLE but the test expects a result of 1.

Given the rules of the puzzle, if you start on floor 2 and up is 1000 floors and down is 999 floors, there is no way you can reach floor 1 with 1 button press.

The first digit it expects is 1. That is not the whole number. It is called âLots of Stepsâ for a reason.

Press Up, press Down - will go up one floor.
Repeat 998 time (1996 press the buttons) - will go up 998 floors, stand 2+ 998 = 1000th floor. Press Down - stand 1000-999 = 1nd floor. In total 1997 press the buttons, not IMPOSSIBLE.

You get past validator 5? Iâm stuck on it as well. Passed all other test cases and validators. According to the known test case âAbove and Belowâ im not sure what else it is testingâŚ hmm. Ready to smash a keyboardâŚ I wish these validators had named tests

@bgura test 5 wants you to answer IMPOSSIBLE

Thanks everyone for the help with test 6. I didnât realise that when it says âexpected 1â that just means the first character and not the entire answer.

Iâve passed all tests now. Woohoo!

blargh, thanks. Iâve got test 5 solved but not validator 5 (just to make sure theres no confusion). Still hacking away asdfjkl;

I solved the question using recursion and it wasnât passing validator 5
I was calling a `step` function recursively
Initially the code was -

``````int up=step(k+a);
int down=step(k-b);
``````

and it didnât pass validator 5 but when i changed it to

``````int down=step(k-b);
int up=step(k+a);
``````

it worked, so obviously the code is still not completely correct but I canât figure out what the problem is

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Well thats really annoyingâŚ That was my issue as well it turns out. I wonder if we overflow the stack or something? How much space do we get??. Argghh, anywayâŚ its passing now

How the heck did you think of that?

Edit: There still may be a bug im overlooking but if thats not the caseâŚ

The FAQ says we get 768 MB and Iâm almost certain it wasnât overflow but Iâm not completely sure.

The code still isnât correct as the test could be reversed and it wouldnât pass, but I stole the 2nd ranked code and modified it a bit to make it work for test case 8 and I think that one should work for all possible cases.

Does anybody know the purpose of validator 6?
Because itâs the only validator that I fail.
It would be enough for me a similar input in order to find out the bug.
Thanks

1 Like

im in the same boat - tried multiple different solution, all of them fail on validator 6 only

Based on my experience with validator 6, I believe it relates to an index out of range issue in your code.

Try running your code with a n=10000 a=1 b=1 k=1 m=10000

When I ran with those values in a Jupyter Notebook I was quickly able to figure out the bug in my code

I think it was a timeout or recursion limit. i ended up optimizing my solution and it worked fine - thanks for the help though

In my case I donât think itâs a timeout problem, because in a test the code was able to count 17997 buttons pressed.
It could be a stupid problem, but I am unable to find it.Could you suggest me some input that gave you trouble?

Maybe add a test with: â2000 3 11 1000 1â or something similar? =)

Hi! I passed all tests but have a problem with validator 6. Could anyone help?

Maybe a problem when the elevator reaches the floor or the roof?

Hi! Solved it without a single loop directive. Solution can be obtained by solving linear Diophantine equation with special restrictions. Extended Euclidean algorithm fits the case perfectly. Loved the puzzle, thank you!

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I would suggest adding better description about how the floors are counted.
Some buildings have the Ground floor at the bottom, and then 1st, 2nd floors upward. âGâ is practically the first floor.
Some buildings count from 1 as the bottom floor.
Some others have basements, -1, -2 floors.
So, for this puzzle, can my position be 0? Or be negative?

Thanks