using System;

​

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public class Employee

    {

        public int Id { get; set; }

​

        public string EmpName { get; set; }

        public decimal Stats { get; set; }

    }

    private static List<Employee> CreateData()

    {

         var employee = new List<Employee>();

         employee.Add

                (

                    new Employee

                    {

                        Id = 1,

                        EmpName = "Abc",

                        Stats=1000

                    }

                );

         employee.Add

                (

                    new Employee

                    {

                        Id = 1,

                        EmpName = "Abc",

                        Stats=3000

                    }

                );

         employee.Add

                (

                    new Employee

                    {

                        Id = 1,

                        EmpName = "Abc",

                        Stats=2000

                    }

                );

         employee.Add

                (

                    new Employee

                    {

                        Id = 2,

                        EmpName = "Pqr",

                        Stats=4000

                    }

                );

         employee.Add

                (

                    new Employee

                    {

                        Id = 2,

                        EmpName = "Pqr",

                        Stats=5000

                    }

                );

         employee.Add

                (

                    new Employee

                    {

                        Id = 2,

                        EmpName = "Pqr",

                        Stats=6000

                    }

                );

        return employee;

    }

    public static void Main()

    {

        var list = CreateData();

        var groupList = list.GroupBy(t => t.Id);

        var testLinq = (from l in list

                    group l by l.Id into grp

                    let part1 = grp.Count()/2

                    let part2 = (int)Math.Ceiling((double)grp.Count()/2)

                    let firstSet = grp.Select(i=>i.Stats).Take(part2)

                    let secondSet = grp.Select(i=>i.Stats).Skip(part1).Take(part2)

                    select new Employee{

                        Id = grp.Key,

                        EmpName = grp.FirstOrDefault().EmpName,

                        Stats = (firstSet.Max() - firstSet.Min()) + (secondSet.Max() - secondSet.Min())

                    }).ToList();

        foreach(var row in testLinq){

            Console.WriteLine(row.Id);

            Console.WriteLine(row.EmpName);

            Console.WriteLine(row.Stats);

        }

        var finalList = new List<Employee>();

        foreach(var grp in groupList){

            int part1 = grp.Count()/2,

                part2 = (int)Math.Ceiling((double)grp.Count()/2);

            var firstSet = grp.Select(i=>i.Stats).Take(part2);

            var secondSet = grp.Select(i=>i.Stats).Skip(part1).Take(part2);

            var total = (firstSet.Max() - firstSet.Min()) + (secondSet.Max() - secondSet.Min());

            finalList.Add(new Employee{

                Id = grp.Key,

                EmpName = grp.FirstOrDefault().EmpName,

                Stats = total

            });

        }   

        foreach(var row in finalList){

            Console.WriteLine(row.Id);

            Console.WriteLine(row.EmpName);

            Console.WriteLine(row.Stats);

        }

    }

}