using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var candidateShifts = new List<AvailabilityPreference>();

        candidateShifts.Add(new AvailabilityPreference{CandidateId = 1, DayOfWeek = 0, ShiftTime = "10-12"});

        candidateShifts.Add(new AvailabilityPreference{CandidateId = 1, DayOfWeek = 1, ShiftTime = "10-12"});

        candidateShifts.Add(new AvailabilityPreference{CandidateId = 2, DayOfWeek = 0, ShiftTime = "10-12"});

        candidateShifts.Add(new AvailabilityPreference{CandidateId = 2, DayOfWeek = 1, ShiftTime = "10-12"});

        candidateShifts.Add(new AvailabilityPreference{CandidateId = 2, DayOfWeek = 2, ShiftTime = "10-12"});

        candidateShifts.Add(new AvailabilityPreference{CandidateId = 3, DayOfWeek = 0, ShiftTime = "10-12"});

        candidateShifts.Add(new AvailabilityPreference{CandidateId = 3, DayOfWeek = 1, ShiftTime = "10-12"});

        candidateShifts.Add(new AvailabilityPreference{CandidateId = 4, DayOfWeek = 1, ShiftTime = "10-12"});

        candidateShifts.Add(new AvailabilityPreference{CandidateId = 5, DayOfWeek = 2, ShiftTime = "10-12"});

        var groupedShifts = from pref in candidateShifts group new {pref.DayOfWeek, pref.ShiftTime}  by pref.CandidateId 

            into result select new { CandidateId = result.Key, ShiftDetails = result.ToList()};

        foreach(var x in groupedShifts.ToList())

        {

            Console.WriteLine(x.CandidateId.ToString() +"-"+ x.ShiftDetails.Count().ToString());

            foreach(var y in x.ShiftDetails)

            {

                Console.WriteLine(y.DayOfWeek.ToString()+ "-" + y.ShiftTime);

            }

        }

    }

}

​

public class AvailabilityPreference

{

    public int CandidateId {get; set;}

    public int DayOfWeek {get; set;}

    public string ShiftTime {get; set;}

}

​