classSolution {

funfrequencySort(s:String):String {

val counts= s

.groupingBy { it }

.eachCount()

val buckets=HashMap<Int,MutableList<Char>>()

for ((char, count)in counts)

buckets.getOrPut(count) {mutableListOf() }.apply { add(char) }

val res=StringBuilder()

for (countin s.length downTo1) {

buckets[count]?.forEach { char->

repeat (count) {

res.append(char)

}

}

}

return res.toString()

}

}

classSolution {

funfrequencySort(s:String):String {

val counts=IntArray (128)

for (cin s)

counts[c.toInt()]++

val sortedCounts= counts

.mapIndexed { i, v-> i to v }

.filter { it.second>0 }

.sortedWith(compareBy({-it.second },{ it.first }))

val res=StringBuilder ()

for ((char, count)in sortedCounts) {

repeat (count) {

res.append(char.toChar())

}

}

return res.toString()

}

}