C# List中分组求和

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

namespace ConsoleApplication22
{
    class MapCross
    {
        public int Id { get; set; }

        public string Name { get; set; }
    }

    class Program
    {
        static void Main(string[] args)
        {
            List<MapCross> list = new List<MapCross>();
            list.Add(new MapCross { Id = 1, Name = "A" });
            list.Add(new MapCross { Id = 2, Name = "B" });
            list.Add(new MapCross { Id = 2, Name = "B" });
            list.Add(new MapCross { Id = 3, Name = "C" });
            list.Add(new MapCross { Id = 3, Name = "C" });
            list.Add(new MapCross { Id = 4, Name = "D" });

            var query = from l in list
                        group l by new { l.Id, l.Name } into g
                        select new
                        {
                            Id = g.Key.Id,
                            Name = g.Key.Name,
                            Count = g.Count(),
                        };

            List<MapCross> listnew = new List<MapCross>();

            foreach (var item in query)
            {
                if (item.Count == 1)
                {
                    MapCross cross = new MapCross();
                    cross.Id = item.Id;
                    cross.Name = item.Name;
                    listnew.Add(cross);
                }
            }
            Console.Read();
        }
    }
}