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CSharp · Console

/Program.cs

using System;
using System.Linq;
using System.Collections.Generic;
					
public class Program
{
	public static void Main()
	{
		var players = new List<Player>{
			new Player{Id = 1, Name = "Player1"},
			new Player{Id = 2, Name = "Player2"},
			new Player{Id = 3, Name = "Player3"},
			new Player{Id = 4, Name = "Player4"},
			new Player{Id = 8, Name = "Player8"},
			new Player{Id = 11, Name = "Player11"}	
		};
		
		var matches = new List<Match>{
			new Match{Id = 10, Name = "Match10", PlayerId = 1, Home = "Y"},
			new Match{Id = 11, Name = "Match11", PlayerId = 1, Home = "Y"},
			new Match{Id = 12, Name = "Match12", PlayerId = 1, Home = "N"},
			new Match{Id = 13, Name = "Match13", PlayerId = 1, Home = "N"},
			new Match{Id = 14, Name = "Match14", PlayerId = 2, Home = "N"},
			new Match{Id = 15, Name = "Match15", PlayerId = 3, Home = "N"},
			new Match{Id = 16, Name = "Match16", PlayerId = 4, Home = "Y"},
			new Match{Id = 17, Name = "Match17", PlayerId = 4, Home = "N"},
			new Match{Id = 19, Name = "Match18", PlayerId = 11, Home = "Y"},
			new Match{Id = 18, Name = "Match19", PlayerId = 11, Home = "N"},
			new Match{Id = 20, Name = "Match20", PlayerId = 11, Home = "N"},
			new Match{Id = 21, Name = "Match21", PlayerId = 1, Home = "N"},
			new Match{Id = 22, Name = "Match22", PlayerId = 1, Home = "Y"},
			new Match{Id = 23, Name = "Match23", PlayerId = 8, Home = "N"},
			new Match{Id = 24, Name = "Match24", PlayerId = 1, Home = "Y"},
		};
		
		
		var playerMatches = players
			.GroupJoin(matches, p => p.Id, m => m.PlayerId, (p, m) => new {player = p, matches = m})
			.Select(x => new {
				PlayerId = x.player.Id,
				PlayerName = x.player.Name,
				Home = x.matches.Where(m => m.Home.StartsWith("Y")).Count()
			});
		
		foreach(var match in playerMatches){
			
			Console.WriteLine(match);
		}
	}
	
	
	public class Player{		
		public long Id;
		public string Name;
	}
	
	public class Match{
		public long Id;
		public string Name;
		public long PlayerId;
		public string Home;
	}
}