How to duplicate array within same array x times?

Question

So, I have made function that return publicKey and I need to duplicate it x times for later use. For example: publicKey: [76, 152, 93, 102, 145, 181] and I need to duplicate it 3 times, so the end result should be [76, 152, 93, 102, 145, 181, 76, 152, 93, 102, 145, 181, 76, 152, 93, 102, 145, 181]. I have tried using var list3 = publicKey*x, but as you can imagine, it didn't work..

fun getPublicKey(privateKey: ArrayList<BigInteger>, 
                 birthDay: BigInteger, 
                 primNumb: BigInteger): ArrayList<BigInteger> {
    val inversMod = birthDay.modInverse(primNumb)
    //println(inversMod)
    val publicKey: ArrayList<BigInteger> = ArrayList()
    for (keyValue in privateKey){
        val pagaiduValue = (keyValue * inversMod).mod(primNumb)
        //println("($keyValue * $inversMod) mod $primNumb = $pagaiduValue")
        publicKey.add(pagaiduValue)
    }
    return publicKey 
}

zsmb13 · Accepted Answer · 2018-02-21 17:12:33Z

3

Here's a short and simple solution:

inline fun <T> Iterable<T>.times(count: Int) = (1..count).flatMap { this }

Can be used like this:

val numbers = listOf(1, 2, 3)
val result = numbers.times(5)
println(result)                 // [1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3]

Perhaps the naming could use some work, times could also be assumed to have the effect of multiplying each element by a given number, repeat could be a better alternative. Also, you might wanna define it on Array<T> and the primitive array types (IntArray, etc) as well.

answered Feb 21, 2018 at 17:12

zsmb13

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