说明：  请编程如下，从键盘输入N名学生的3门成绩（数学、语文、英语），分别统计每个学生的平均成绩和总成绩，然后分别按照平均成绩和总成绩从大到小输出。（在主函数中输入N的值（通过带参数的主函数获取），四个子函数求平均成绩、总成绩、平均成绩从大到小输出、总成绩从大到小输出。 注：提示，此题需要用结构体、指针实现。
(Please programming follows N students in three grades (mathematics, language, and English), the input from the keyboard, the statistics of each student' s grade point average and a total score, then according to the average scores and the total score from largest to smallest output. (The value of N (acquisition) with the main function of the parameters are entered in the main function, four subfunctions averaging results, total score and grade point average from largest to smallest output total score from largest to smallest output Note: prompt, this title need to achieve with the structure, the pointer.)