Brilliant numbers: Difference between revisions
→{{header|Scala}}
Line 1,871:
=={{header|Scala}}==
<syntaxhighlight lang="scala">
val primes = 2 #:: LazyList.from(3, 2) // simple prime
.filter(p => (3 to math.sqrt(p).ceil.toInt by 2).forall(p % _ > 0))
def brilliantSemiPrimes(limit: Int): Seq[Int] = {
def iter(primeList: LazyList[Int], bLimit: Int, acc: Seq[Int]): Seq[Int] = {
val (start, tail) = (primeList.head, primeList.tail)
val brilliants = primeList
.takeWhile(_ <= bLimit)
.map(_ * start)
.takeWhile(_ <= limit)
if (brilliants.isEmpty) return acc
val bLimit1 = if (tail.head > bLimit) 10 * bLimit else bLimit
iter(tail, bLimit1, brilliants.toSeq ++ acc)
}
iter(primes, 10, Seq()).sorted
}
@main def main = {
val start = System.currentTimeMillis
val brList = brilliantSemiPrimes(1500).take(100)
val duration = System.currentTimeMillis - start
for (group <- brList.grouped(20))
println(group.map("%4d".format(_)).mkString(" "))
println(s"time elapsed: $duration ms\n")
for (limit <- (1 to 6).map(math.pow(10,_).toInt)) {
val start = System.currentTimeMillis
val (bril, index) = brilliantSemiPrimes((limit * 1.25).toInt)
.zipWithIndex
.dropWhile((b, _i) => b < limit)
.take(1).head
val duration = System.currentTimeMillis - start
println(f"first >= $limit%7d is $bril%7d at position ${index+1}%5d [time(ms) $duration%2d]")
}
}
</syntaxhighlight>
{{out}}
<pre>
</pre>
=={{header|Sidef}}==
| |||