func biggerIsGreater(w string) string {
    str := strings.Split(w, "")

    s_len := len(str)

    for i := 1; i < len(str); i++ {

        curr_index := s_len - i - 1
        curr := str[curr_index]

        rest := str[curr_index+1:]

        sort.Slice(rest, func(i, j int) bool {
            return rest[i] < rest[j]
        })

        for j, v := range rest {
            if v > curr {
                initial := strings.Join(str[:curr_index], "")
                rest = append(rest[:j], rest[j:]...)

                rest[j] = curr

                sort.Slice(rest, func(i, j int) bool {
                    return rest[i] < rest[j]
                })

                return initial + v + strings.Join(rest, "")
            }
        }

    }

    return "no answer" 
}