查找自定义类型的列表中最大计数 [英] Find max count of a list of custom types

问题描述

我有一个模拟的应用程序，其中一个继承链像
员工，经理，president 等。

I have a mock application where an inheritance chain like Employee,Manager,President etc.

Employee类看起来像

The Employee class looks like

class Employee
    {
        public int EmployeeId { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public DateTime HireDate { get; set; }

        public Employee() 
        { 
        }
    }

和Manager类看起来像

and the Manager class looks like

 class Manager : Employee
    {

        private List<Employee> employeesManaged = new List<Employee>();
        public List<Employee> EmployeesManaged
        {
            get { return employeesManaged; }
            set { employeesManaged = value; }
        }
    }

我想编写发现谁管理的大部分员工（其EmployeesManaged.Count财产是最大的）管理者的方法。我现在有两个问题。

I would like to write a method that finds the manager who manages the most employees (whose EmployeesManaged.Count property is the largest). I have two problems currently.

1. 你将在code见下面我给每个经理手动添加到列表变量。这不是一个长期的解决方案。什么是解决这一有效，简洁的方式？

1. as you'll see in the code below I have to manually add each Manager to a List variable. This isn't a long-term solution. What would be an effective, concise manner of solving this?

我的LINQ语法不正确。

my Linq syntax is incorrect.

我想第一个问题是最pressing。如果有1000个Employee对象，我怎么会绕过每增加一个列表？

I think the first problem is most pressing. If there were 1000 Employee objects, how would I circumvent adding each one to a list?

 public static Manager  GetBestManager(List<Manager> managerList)
        {
            Manager m = managerList.Select(x => x.EmployeesManaged).Max();

        }

我的主要方法

Employee e = new Employee();
            e.EmployeeId = 101;
            e.FirstName = "Tom";
            e.LastName = "Jones";
            e.HireDate = DateTime.Now.Subtract(TimeSpan.FromDays(40));

            Employee e2 = new Employee();
            e2.EmployeeId = 102;


            Employee e3 = new Employee();
            e3.EmployeeId = 103;


            Manager m = new Manager();
            m.EmployeeId = 201;
            m.EmployeesManaged.Add(e);
            m.EmployeesManaged.Add(e2);

            Manager m2 = new Manager();
            m2.EmployeesManaged.Add(e3);

            List<Manager> mList = new List<Manager>();
            mList.Add(m);
            mList.Add(m2);
            Manager.GetBestManager(mList);

与当前的语法我得到的错误无法Employee类型隐式转换为经理

with the current syntax I get the error 'Cannot implicitly convert type Employee to Manager

推荐答案

1），这取决于在数据的来源。一个数据库，从磁盘文件，内存中的集合。通常情况下，列表或任何结构是由源决定。

1) It depends on where the data is coming from. A database, file from disk, in memory collection. Often the List or whatever structure is determined by the source.

2）您的LINQ是获得最大数量，而不是管理​​最高计数。尝试：

2) Your LINQ is getting the max number, not the Manager with the highest count. Try:

public static Manager GetBestManager(List<Manager> managerList)
{
    Manager m = managerList.OrderByDescending(x => x.EmployeesManaged.Count).First();
    return m;
}

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