C# Online Compiler | .NET Fiddle

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

					
public class Program
{
	public static void Main()
	{
		List<Employee> employees = new List<Employee>
		{
			new Employee { ID = 1, Name = "Alice Johnson", Position = "Manager", Department = "Sales", HireDate = new DateTime(2018, 05, 23), Salary = 90000 },
			new Employee { ID = 2, Name = "Bob Smith", Position = "Salesperson", Department = "Sales", HireDate = new DateTime(2020, 03, 15), Salary = 60000 },
			new Employee { ID = 3, Name = "Charlie Brown", Position = "Developer", Department = "IT", HireDate = new DateTime(2019, 02, 11), Salary = 80000 },
			new Employee { ID = 4, Name = "Diane Miller", Position = "Manager", Department = "IT", HireDate = new DateTime(2017, 04, 29), Salary = 95000 },
			new Employee { ID = 5, Name = "Evan Rogers", Position = "Salesperson", Department = "Sales", HireDate = new DateTime(2021, 01, 09), Salary = 65000 }
		};
		
		// Step 1: Identify the department with the highest average salary
		var highestAvgSalaryDept = employees
			.GroupBy(e => e.Department)
			.Select(group => new { Department = group.Key, AverageSalary = group.Average(e => e.Salary) })
			.OrderByDescending(result => result.AverageSalary)
			.FirstOrDefault();

		Console.WriteLine($"Department with Highest Average Salary: {highestAvgSalaryDept.Department}");

		// Step 2: Within this department, find the position with the highest average salary
		var highestAvgSalaryPosition = employees
			.Where(e => e.Department == highestAvgSalaryDept.Department)
			.GroupBy(e => e.Position)
			.Select(group => new { Position = group.Key, AverageSalary = group.Average(e => e.Salary) })
			.OrderByDescending(result => result.AverageSalary)
			.FirstOrDefault();

		Console.WriteLine($"Position with Highest Average Salary in {highestAvgSalaryDept.Department}: {highestAvgSalaryPosition.Position}");

		// Step 3: List all employees for the position identified in step 2, in descending order of their hire date
		var employeesInPosition = employees
			.Where(e => e.Position == highestAvgSalaryPosition.Position && e.Department == highestAvgSalaryDept.Department)
			.OrderByDescending(e => e.HireDate)
			.ToList();

		Console.WriteLine($"Employees in {highestAvgSalaryPosition.Position} position, sorted by hire date:");
		foreach (var employee in employeesInPosition)
		{
			Console.WriteLine($"- {employee.Name}, Hired: {employee.HireDate.ToString("yyyy-MM-dd")}");
		}


	}
}

public class Employee
{
    public int ID { get; set; }
    public string Name { get; set; }
    public string Position { get; set; }
    public string Department { get; set; }
    public DateTime HireDate { get; set; }
    public decimal Salary { get; set; }
}

 
using System;
using System.Collections.Generic;
using System.Linq;
​
                    
public class Program
{
    public static void Main()
    {
        List<Employee> employees = new List<Employee>
        {
            new Employee { ID = 1, Name = "Alice Johnson", Position = "Manager", Department = "Sales", HireDate = new DateTime(2018, 05, 23), Salary = 90000 },
            new Employee { ID = 2, Name = "Bob Smith", Position = "Salesperson", Department = "Sales", HireDate = new DateTime(2020, 03, 15), Salary = 60000 },
            new Employee { ID = 3, Name = "Charlie Brown", Position = "Developer", Department = "IT", HireDate = new DateTime(2019, 02, 11), Salary = 80000 },
            new Employee { ID = 4, Name = "Diane Miller", Position = "Manager", Department = "IT", HireDate = new DateTime(2017, 04, 29), Salary = 95000 },
            new Employee { ID = 5, Name = "Evan Rogers", Position = "Salesperson", Department = "Sales", HireDate = new DateTime(2021, 01, 09), Salary = 65000 }
        };
        
        // Step 1: Identify the department with the highest average salary
        var highestAvgSalaryDept = employees
            .GroupBy(e => e.Department)
            .Select(group => new { Department = group.Key, AverageSalary = group.Average(e => e.Salary) })
            .OrderByDescending(result => result.AverageSalary)
            .FirstOrDefault();

Cached Result

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