280
submitted 5 months ago by [email protected] to c/[email protected]
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[-] [email protected] 97 points 5 months ago

While this doesn't work all the time, when it does, it's really fast. Similar to the isPrime function, it's correct most of the time and is much faster than alternative implementations:

function isPrime(number) {
    return false;
}
[-] [email protected] 36 points 5 months ago* (last edited 5 months ago)

What your code can do is run this first and if it returns false then do a quick double check using a traditional isPrime function. Really speeds things up!

[-] [email protected] 25 points 5 months ago

I mean, it has a 99.999%+ success rate on a large enough sample and I can live with that.

[-] [email protected] 6 points 5 months ago

Nah, you've always got to check the corner cases. It's a variation on Murphy's Law - you don't encounter corner cases when you're developing a program but corner cases are 99 percent of an everyday user's interaction.

[-] [email protected] 5 points 5 months ago

Good idea, but it would be much faster if you do the double-check on true instead.

[-] [email protected] 1 points 5 months ago

This is a power(ful) idea.

Are my stats/programmers in the house?

[-] [email protected] 4 points 5 months ago

Better. Return true if the number is in a stored list of known primes, otherwise return false right away. But then, start a separate thread with an actual verification algorithm. When the verification is done, if it was actually a prime number, you just crash the program with a WasActuallyPrime exception.

[-] [email protected] 16 points 5 months ago

asymptotically this is 100% correct!

[-] [email protected] 5 points 5 months ago

What would be the accuracy on something like a 64bit unsigned integer?

[-] [email protected] 2 points 5 months ago

50/50 chance of being right in O(1) time

[-] [email protected] 8 points 5 months ago

It's right much more often than just 50/50.

[-] [email protected] 5 points 5 months ago

50/50 would be for isOdd with the same implementation

[-] [email protected] 3 points 5 months ago

Primes are not that common especially as numbers get bigger.

It'll be right the vast majority of times.

[-] [email protected] 36 points 5 months ago
[-] [email protected] 35 points 5 months ago

Copilot is fucking killing it these days.

[-] [email protected] 27 points 5 months ago

inplace sort be like:

def sort(list: list):
    list.clear()
[-] [email protected] 21 points 5 months ago
[-] [email protected] 11 points 5 months ago

Besides the obvious flaws... is that parameter a list named list, shadowing the list() constructor?

[-] [email protected] 5 points 5 months ago

It works as long as you don't call list() within that function.

[-] [email protected] -2 points 5 months ago
[-] [email protected] 3 points 5 months ago

Well duh. I wonder what happens if you shadow the list constructor and try to use it as a type hint...

def foo(list: list):
  def bar(thingies: list):
    pass
[-] [email protected] 9 points 5 months ago

you can even have a case where you return the first element of the list if the list is not empty, and it will still be O(1).

[-] [email protected] 12 points 5 months ago

you can make it sort the first k elements and it will still be O(1). Set k high enough and it might even be useful

[-] [email protected] 5 points 5 months ago

I set k to 50,000,000,000... that's more items than my shitty computer can fit in memory (including swsp) but I am now happy to celebrate my O(1) algorithm.

[-] [email protected] 1 points 5 months ago

By that logic, any sorting implementation is O(1), as the indexing variable/address type has limited size

[-] [email protected] 7 points 5 months ago* (last edited 5 months ago)

Honey, wake up. The new Def Leppard Album just dropped

this post was submitted on 28 Jan 2024
280 points (95.5% liked)

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