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o(1) statistical prime approximation (lemmy.blahaj.zone)

submitted 1 month ago* (last edited 1 month ago) by not_IO@lemmy.blahaj.zone to c/programmer_humor@programming.dev

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https://cosocial.ca/@mhoye/116111505546606451

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[-] JustARegularNerd@lemmy.dbzer0.com 15 points 1 month ago

I'm struggling to follow the code here. I'm guessing it's C++ (which I'm very unfamiliar with)

bool is_prime(int x) {
    return false;
}

Wouldn't this just always return false regardless of x (which I presume is half the joke)? Why is it that when it's tested up to 99999, it has a roughly 95% success rate then?

[-] kraftpudding@lemmy.world 35 points 1 month ago

I suppose because about 5% of numbers are actually prime numbers, so false is not the output an algorithm checking for prime numbers should return

[-] JustARegularNerd@lemmy.dbzer0.com 11 points 1 month ago

Oh I'm with you, the tests are precalculated and expect a true to return on something like 99991, this function as expected returns false, which throws the test into a fail.

Thank you for that explanation