如何使用linq对缺少的值进行分组和计数

using System;
using System.Collections.Generic;
using System.Linq;

public class Student
{
    public string Name { get; set; }
    public int Age { get; set; }
}

public class Program
{
    public static void Main()
    {
        // 准备数据源
        var students = new List<Student>
        {
            new Student { Name = "Alice", Age = 18 },
            new Student { Name = "Bob", Age = 20 },
            new Student { Name = "Charlie", Age = 18 },
            new Student { Name = "David", Age = 22 },
            new Student { Name = "Eve", Age = 20 }
        };

        // 使用LINQ查询
        var groupedData = students.GroupBy(s => s.Age);
        var result = groupedData.Select(g => new { Age = g.Key, Count = g.Count() });

        // 处理结果
        foreach (var item in result)
        {
            Console.WriteLine($"Age: {item.Age}, Count: {item.Count}");
        }
    }
}

Age: 18, Count: 2
Age: 20, Count: 2
Age: 22, Count: 1