每名学生需要如下描述：学号、姓名、成绩。成绩保留小数点一位。试编制一程序完成学生的录入和输出。最终对所有学生的成绩进行从高到低的排序，并且输出排序结果，并且得出平均分，并且保留一位小数并且输出。-Needs of each student described as follows: Student ID, name, performance. Results 1 to retain a decimal point. Try to prepare a student entry process is completed and output. The final results of all students to sort from high to low, and the output of sorting results, and the average score obtained, and retained a decimal, and the output.