[プログラマーレベル3]ベストアルバム

に質問

せいげんじょうけん

💡 に答える

class Solution {
    fun solution(genres: Array<String>, plays: IntArray): IntArray {
        var answer = intArrayOf()
        val genres = genres.mapIndexed { index, genre -> Pair(genre, index) }
        val genresMap = genres.groupBy( {it.first}, {it.second} )
        var genresMapWithPlays = genresMap.mapValues { it.value.map { Pair(it, plays.get(it))} }.mapValues { it.value.sortedByDescending { it. second } }
        val playsByGenre = genresMap.mapValues{ it.value.fold(0) { acc, num -> acc + plays.get(num) } }.toList().sortedByDescending { it.second }.toMap()
                
        playsByGenre.forEach { genre, totalPlay ->
            val songList = genresMapWithPlays.get(genre)
            
            if(songList!!.size == 1)
                answer += (songList[0].first)
            else {
                answer += (songList[0].first)
                answer += (songList[1].first)
            }
        }
        
        return answer
    }
}