package leetcode
import (
"sort"
)
func frequencySort(s string) string {
if s == "" {
return ""
}
sMap := map[byte]int{}
cMap := map[int][]byte{}
sb := []byte(s)
for _, b := range sb {
sMap[b]++
}
for key, value := range sMap {
cMap[value] = append(cMap[value], key)
}
var keys []int
for k := range cMap {
keys = append(keys, k)
}
sort.Sort(sort.Reverse(sort.IntSlice(keys)))
res := make([]byte, 0)
for _, k := range keys {
for i := 0; i < len(cMap[k]); i++ {
for j := 0; j < k; j++ {
res = append(res, cMap[k][i])
}
}
}
return string(res)
}