hhariri

fun <T, R, C: MutableCollection<in R>> Iterable<T>.flatMapTo(result: C, transform: (T) -> Iterable<R>) : C

hhariri

fun albumAndTrackLowerThanGivenSeconds_v2(durationInSeconds: Int, albums: List<Album>): List<Pair<String, String>> {
    return albums.flatMap {
        val album = it.title
        it.tracks.filter {
            it.durationInSeconds <= durationInSeconds
        }.map {
            Pair(album, it.title)
        }
    }
}

hhariri

fun <T, R> Iterable<T>.flatMap(transform: (T)-> Iterable<R>) : List<R>

hhariri

fun albumAndTrackLowerThanGivenSeconds_v1(durationInSeconds: Int, albums: List<Album>): List<Pair<String, String>> {

    val list = arrayListOf<Pair<String, String>>()
    albums.forEach {
        val album = it.title
        it.tracks.filter {
            it.durationInSeconds <= durationInSeconds
        }.map {
            list.add(Pair(album, it.title))
        }

hhariri

fun nameAndTotalTime_v2(albums: List<Album>): List<Pair<String, Int>> {
    return albums.map {
        Pair(it.title, it.tracks.map { it.durationInSeconds }.reduce { x, y -> x +y })
    }
}

hhariri

fun sumOfInts(list: List<Int>): Int {
    return list.reduce { (x, y) -> x + y}
}

hhariri

fun nameAndTotalTime_v1(albums: List<Album>): List<Pair<String, Int>> {
    return albums.map {
        var total = 0
        it.tracks.forEach {
            total += it.durationInSeconds
        }
        Pair(it.title,total)
    }
}

hhariri

data class Track(val title: String, val durationInSeconds: Int)

val pinkFloyd = listOf(
        Album("The Dark Side of the Moon", 1973, 2, 1,
                listOf(Track("Speak to Me", 90),
                        Track("Breathe", 163),
                        Track("On he Run", 216),
                        Track("Time", 421),
                        Track("The Great Gig in the Sky", 276),
                        Track("Money", 382),

hhariri

fun <T, R> Collection<T>.map(transform : (T) -> R) : List<R>

hhariri

fun topUSandUK_hits_years_v2(albums: List<Album>): List<Int> {
    return albums.filter {
        (it.chartUK == 1 && it.chartUS == 1)
    }.map {
        it.year
    }
}