using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Text;

​

namespace ConsoleApplication3

{

    class Program

    {

        static void Main(string[] args)

        {

            var playList = new Dictionary<int, HashSet<int>>(); //(CLIENT_ID,ListOfSong)

            using (StreamReader streamReader = new StreamReader("exhibitA-input.csv", Encoding.UTF8, true, bufferSize: 4096))

            {

                String line;

                if (streamReader.ReadLine() != null) //skip header

                    while ((line = streamReader.ReadLine()) != null)

                    {

                        var columns = line.Split('\t');

                        if (columns[3].StartsWith("10/08/2016"))

                        {

                            var ClientId = Int32.Parse(columns[2]);

                            var SongId = Int32.Parse(columns[1]);

                            if (playList.ContainsKey(ClientId))

                                playList[ClientId].Add(SongId);

                            else

                                playList.Add(ClientId, new HashSet<int>() { SongId });

                        }

​

​

                    }

            }

            var resultTable = playList.GroupBy(x => x.Value.Count())

                .ToDictionary(x => x.Key, x => x.Count());

​

​

​

        }

​

    }

​

​

}

​