29 lines
862 B
Scala
29 lines
862 B
Scala
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// Scala primes
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// This to my mind may not be the fastest algorithm,
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// I would think printing when finding would be better,
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// especially on memory, then storing the thing in a list
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// and then running mkString on it, but it already
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// outperforms java for me, so here it is
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object Primes {
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def main(args: Array[String]) {
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if (args.length < 1) {
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println("Usage: scala Primes [MAX]")
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} else print(primes(3, List(), args(0).toInt).mkString("\n") + "\n")
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}
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def is_prime(num: Int): Boolean = {
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def prime_loop(i: Int, max: Int): Boolean =
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if (i > max) true
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else if (num % i == 0) false
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else prime_loop(i+2, max)
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prime_loop(3, scala.math.sqrt(num).ceil.toInt)
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}
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def primes(i: Int, acc: List[Int], max: Int): List[Int] =
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if (i >= max) acc
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else if (is_prime(i)) primes(i+2, acc ++ List(i), max)
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else primes(i+2, acc, max)
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}
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