gistfile1.kt

import java.security.SecureRandom

/**
 * Created by alexeypushkarev on 04.06.17.
 */

fun randomArrayOfUniques(size: Int, maxValue: Int): List<Int> {
    if (size > maxValue) {
        throw IllegalArgumentException("maxValue should be greater than size")
    }
    val generatedList = mutableListOf<Int>()
    val generatedArray = IntArray(size, { i -> generateUnique(generatedList, maxValue) })
    return generatedArray.toList()
}

fun generateUnique(alreadyUsedValues: MutableList<Int>, maxVal: Int): Int {
    val random: SecureRandom = SecureRandom.getInstance("SHA1PRNG")
    var rnd: Int = random.nextInt(maxVal)

    while (alreadyUsedValues.contains(rnd)) {
        rnd = random.nextInt(maxVal)
    }

    alreadyUsedValues.add(rnd)
    return rnd
}