func solution(_ k:Int, _ m:Int, _ score:[Int]) -> Int {
var answer = 0
var score = score.sorted{$0 > $1}
var start = m-1
while start < score.count {
answer += m*score[start]
start += m
}
return answer
}func solution(_ k:Int, _ m:Int, _ score:[Int]) -> Int {
let s = score.sorted(by: >)
return stride(from: m-1, to: score.count, by: m)
.reduce(0) { $0 + s[$1] * m }
}stride, reduce 사용
