c# - C#中自定义rank函数的优化

Question

我写了学生课的代码到排名 他们根据他们的标记。代码工作准确，结果如下

Name:B  Marks:30    Rank:1
Name:C  Marks:30    Rank:1
Name:A  Marks:20    Rank:3
Name:D  Marks:10    Rank:4

但我需要对其进行优化，以便处理它不会花费太多时间。下面是代码

public List<Students> GetRanks(List<Students> students)
{
    List<Students> rStudents = new List<Students>();
    students = students.OrderByDescending(a => a.marks).ToList();
    for (int i = 0; i < students.Count; i++)
    {
        Students stu = new Students();
        stu.Id = students[i].Id;
        stu.Name = students[i].Name;
        stu.marks = students[i].marks;

        if (i > 0 && students[i].marks == students[i - 1].marks)
        {
            stu.rank = rStudents.Select(a => a.rank).LastOrDefault();
        }
        else
        {
            stu.rank = i + 1;
        }
        rStudents.Add(stu);
    }
    return rStudents;
}

List<Students> students = new List<Students>() {
new Students() { Id = 1, Name = "A", marks = 20 },
new Students() { Id = 1, Name = "B", marks = 30 },
new Students() { Id = 1, Name = "C", marks = 30 },
new Students() { Id = 1, Name = "D", marks = 10 },
};

List<Students> rStudents = GetRanks(students);
            
            
public class Students
{
    public int Id { get; set; }
    public string Name { get; set; }
    public double marks { get; set; }
    public int rank { get; set; }
}


foreach (Students s in GetRanks(students))
{
    Console.WriteLine($"Name:{s.Name}\tMarks:{s.marks}\tRank:{s.rank}");
}

Answer 1

删除不必要的资源。并使用 产量会对大数据的性能产生影响。更少的行和更多的可读性。
如果您从 获取数据数据库更好的主意是在那里对它们进行排序然后获取它们。

  public static IEnumerable<Students> GetRanks(List<Students> students)
  {
      List<Students> rStudents = students.OrderByDescending(a => a.marks).ToList();
      for (int i = 0; i < rStudents.Count; i++)
      {
        if (i > 0 && rStudents[i].marks == rStudents[i - 1].marks)
          {
              rStudents[i].rank = rStudents[i - 1].rank;
          }
          else
          {
              rStudents[i].rank = i + 1;
          }
          yield return rStudents[i];
      }
  }