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:
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!
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.
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.
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; }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!
I mean, it has a 99.999%+ success rate on a large enough sample and I can live with that.
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.
Good idea, but it would be much faster if you do the double-check on true instead.
This is a power(ful) idea.
Are my stats/programmers in the house?
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.
asymptotically this is 100% correct!
What would be the accuracy on something like a 64bit unsigned integer?
WolframAlpha estimates PrimePi[2^64-1] to be about 4.15829E17, so about 97.7%
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50/50 chance of being right in O(1) time
It’s right much more often than just 50/50.
50/50 would be for
isOddwith the same implementationPrimes are not that common especially as numbers get bigger.
It’ll be right the vast majority of times.