设计一个程序统计某个班全体学生 3 门课的考试成绩。 要求能输入学生人数，并按编号从小到大的顺序依次输入学生的成绩，再统计出每门课程的全班总分、平均分及每个考生所有考试的总分和平均分。

设计这样一个程序可以分为以下几个步骤：

1. 定义数据结构：创建一个名为`Student`的类，包含属性如姓名、学号（用于唯一标识）、以及一个字典（例如`scores`），用于存储三门课程的成绩。

class Student:
    def __init__(self, id):
        self.id = id
        self.scores = {'math': 0, 'english': 0, 'science': 0}
    
    def add_score(self, subject, score):
        self.scores[subject] = score

    def total_scores(self):
        return sum(self.scores.values())

    def average_scores(self):
        if len(self.scores) == 0:
            return 0
        else:
            return self.total_scores() / len(self.scores)

2. 创建一个`Class`类，用于管理学生列表：

class Class:
    def __init__(self):
        self.students = []

    def add_student(self, student_id):
        new_student = Student(student_id)
        self.students.append(new_student)

    def input_scores(self):
        for i in range(len(self.students)):
            print(f"请输入学生 {i+1} 的各科成绩:")
            for subject in ['math', 'english', 'science']:
                score = int(input(f"{subject}: "))
                self.students[i].add_score(subject, score)

    def calculate_totals(self):
        totals = {'math': 0, 'english': 0, 'science': 0}
        for student in self.students:
            for subject, score in student.scores.items():
                totals[subject] += score

        return totals, [student.total_scores() for student in self.students]

    def calculate_averages(self):
        class_totals, individual_totals = self.calculate_totals()
        avg_class = {subject: class_totals[subject] / len(self.students) for subject in class_totals}
        avg_indiv = [student.average_scores() for student in self.students]
        
        return avg_class, avg_indiv

3. 主函数`main`，用于交互式操作：

def main():
    num_students = int(input("请输入学生人数: "))
    class_instance = Class()
    
    for _ in range(num_students):
        class_instance.add_student(_ + 1)

    class_instance.input_scores()

    class_totals, indiv_totals = class_instance.calculate_totals()
    class_averages, indiv_averages = class_instance.calculate_averages()

    print("\n班级成绩汇总:")
    for subject, total in class_totals.items():
        print(f"{subject} 总分: {total}, 平均分: {class_averages[subject]}")

    print("\n每位学生成绩汇总及平均分:")
    for i, student_id in enumerate(class_instance.students):
        print(f"学生{student_id.id}:")
        print(f"总分: {indiv_totals[i]}, 平均分: {indiv_averages[i]}")

if __name__ == "__main__":
    main()