Community Puzzle - Gravity Centrifuge Tuning

Puzzles
#1

Gravity Centrifuge Tuning is very instructive. I suggest everyone to read the titles of the tests to get a clue.

There is one test that is at odds with the puzzle description though. The “Constraints” section states that “N > 0”, but the “Wait, what?” test sets N to 0. It’s probably easier to amend the constraint. If you solve it before the text is changed… be aware of that.

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#2

I have just updated the constraints section.
Thanks for your carefulness.

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#3

Beautiful puzzle. I enjoyed it a lot :slight_smile:

Zeckendorf can indeed be proud

Kudos to the puzzle writer. Very very elegant.

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#4

Hi, I’m trying to solve this puzzle with javascript,
Any clue how to manage the integer overflow?

Seems there is no BigInt() library (on spidermonkey compiler), how I’m supposed to save N (number of tumbles) like on the last test:
"Zeckendorf would be proud of you"?

Even if somehow I managed to work on it’s string representation, and find the binary bitstream (as string), how I can convert the bitstream to octal without overflow?

#5

You are correct that this is much harder in some languages due to the lack of bignum support . For the conversion at the end you can work a single character at a time - every 3 binary bits is one octal character.

#6

Well ok it’s harder (and honestly, why would you use such languages when there are alternatives available? I digress), but I take offense at the “much harder” distinction: if your algorithm is sound, you don’t need any of the “hard” operations, and you can trivially implement them all on a string or bitfield or whatever.

That’s supposed to be way easier than the initial conversion from decimal to your internal representation, whatever it is.

#7

You don’t think it’s a bug that I can’t use BigInt()? (there is BigInt() in node but not in spidermonkey).

How is it possible to find the N tumbles if I can’t reach the number due the overflow?

You can see that the puzzle starts with var N = BigInt(readline()); example:

But you get

Errors
ReferenceError: BigInt is not defined
at Answer.js.null on line 6

image.png1426×728 229 KB

I’ll try explain the problem:

The way I’m trying to solve is building N, from then is just binary to octal.
but I can’t get to N (in node.js I can) due the overflow.

#8

I see three ways do solve that:

  • Find a smarter solution that doesn’t rely on big integers (for this problem I don’t think there is one)
  • Write your own BigInteger functions
  • Use another language that supports it (C# and Java have BigInteger libraries for example, Python supports them natively)