//别的大佬写的,我加了注释
func trans(s string, n int) string {
	strList := strings.Split(s, " ")
	// reverse
	for i, j := 0, len(strList)-1; i < j; i, j = i+1, j-1 {
		strList[i], strList[j] = strList[j], strList[i]
	}
	result := make([]string, 0, len(strList))
	for i, _ := range strList {
		//
		temp := []byte(strList[i])
		for j, _ := range temp {
			//A的ASC值为65,Z为90
			//a为97,z为122

			//小写变大写
			if temp[j] >= 97 {
				temp[j] -= 32
				//大写变小写
			} else if temp[j] <= 90 {
				temp[j] += 32
			}
		}
		//将结果转化为string保存进数组
		result = append(result, string(temp))
	}
	//用空格将字符串拼接你起来
	return strings.Join(result, " ")
}