Generates list of other participants each person have to give a gift to every day.

GiftAdventCalendarMachine.kt

import java.io.File

/**
 * Advent calendar gift generator
 *
 * Generates list of other participants each person have to give a gift to every day.
 */
fun main() {
    println("Pass a list of participants separated by \",\"")
    val santas: List<String> = readln().split(',')

    val santaToPersonAndDayList = santas.associateWith {
        (1..24).toSet().shuffled()
    }
        .map { (santa, bags) ->
            val bag = bags.toMutableSet()
            val santasWithoutSanta = santas.toMutableList().apply { remove(santa) }

            var currentSanta = 0
            val map = mutableMapOf<Int, String>()
            while (bag.isNotEmpty()) {
                val santa = santasWithoutSanta[currentSanta % santasWithoutSanta.size]
                val day = bag.first()
                map[day] = santa
                bag.remove(day)
                currentSanta++
            }
            santa to map.toSortedMap()

        }.toMap()

    santaToPersonAndDayList.forEach { (santa, giftsMap) ->
        File("src", "$santa.txt")
            .printWriter()
            .use { out ->
                out.println("HoHoHo $santa! This is your gift list:")
                giftsMap.forEach { (day, person) ->
                    out.println("$day $person")
                }
                out.println("-----------------------------------")
                out.println("Generated with giftmachine v2.137")
            }
    }

}