func reverseWords(s string) string {
res,tmp := "",""
for i := len(s) - 1; i >= 0; i-- {
if s[i] != ' ' {
tmp = string(s[i]) + tmp
} else if tmp != "" {
res = getStr(res, tmp)
tmp = ""
}
}
if tmp != "" {
res = getStr(res, tmp)
}
return res
}
func getStr(res, tmp string) string {
if len(res) != 0 {
res += " "
}
return res + tmp
}