Jordan-Pólya numbers: Difference between revisions

</pre>

=={{header|Kotlin}}==

{{trans|Java}}

<syntaxhighlight lang="Kotlin">

import java.util.*

object JordanPolyaNumbers {

private val jordanPolyaSet = TreeSet<Long>()

private val decompositions = HashMap<Long, TreeMap<Int, Int>>()

@JvmStatic

fun main(aArgs: Array<String>) {

createJordanPolya()

val belowHundredMillion = jordanPolyaSet.floor(100_000_000L)

val jordanPolya = ArrayList(jordanPolyaSet)

println("The first 50 Jordan-Polya numbers:")

for (i in 0 until 50) {

print(String.format("%5s%s", jordanPolya[i], if (i % 10 == 9) "\n" else ""))

}

println()

println("The largest Jordan-Polya number less than 100 million: $belowHundredMillion")

println()

for (i in listOf(800, 1050, 1800, 2800, 3800)) {

println("The $i th Jordan-Polya number is: ${jordanPolya[i - 1]} = ${toString(decompositions[jordanPolya[i - 1]]!!)}")

}

}

private fun createJordanPolya() {

jordanPolyaSet.add(1L)

val nextSet = TreeSet<Long>()

decompositions[1L] = TreeMap()

var factorial = 1L

for (multiplier in 2..20) {

factorial *= multiplier

val iterator = jordanPolyaSet.iterator()

while (iterator.hasNext()) {

var number = iterator.next()

while (number <= Long.MAX_VALUE / factorial) {

val original = number

number *= factorial

nextSet.add(number)

decompositions[number] = TreeMap(decompositions[original]!!)

decompositions[number]?.merge(multiplier, 1) { a, b -> a + b }

}

}

jordanPolyaSet.addAll(nextSet)

nextSet.clear()

}

}

private fun toString(aMap: Map<Int, Int>): String {

return aMap.entries.joinToString(separator = " * ") { (key, value) ->

"$key!${if (value == 1) "" else "^$value"}"

}

}

}

fun main(args: Array<String>) {

JordanPolyaNumbers.main(arrayOf<String>())

}

</syntaxhighlight>

{{out}}

<pre>

The first 50 Jordan-Polya numbers:

1 2 4 6 8 12 16 24 32 36

48 64 72 96 120 128 144 192 216 240

256 288 384 432 480 512 576 720 768 864

960 1024 1152 1296 1440 1536 1728 1920 2048 2304

2592 2880 3072 3456 3840 4096 4320 4608 5040 5184

The largest Jordan-Polya number less than 100 million: 99532800

The 800 th Jordan-Polya number is: 18345885696 = 2!^2 * 4!^7

The 1050 th Jordan-Polya number is: 139345920000 = 2! * 5!^3 * 8!

The 1800 th Jordan-Polya number is: 9784472371200 = 2!^15 * 4!^2 * 6!^2

The 2800 th Jordan-Polya number is: 439378587648000 = 7! * 14!

The 3800 th Jordan-Polya number is: 7213895789838336 = 2!^16 * 4!^8