using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        List<Package> packages =

            new List<Package>

                { new Package { Company = "Adventure", Weight = 25.2, TrackingNumber = 89453312L },

                  new Package { Company = "Lucerne Publishing", Weight = 18.7, TrackingNumber = 89112755L },

                  new Package { Company = "Wingtip Toys", Weight = 6.0, TrackingNumber = 299456122L },

                  new Package { Company = "Adventure", Weight = 33.8, TrackingNumber = 4665518773L } };

​

        var dictionary = packages

            .GroupBy(p => p.Company)

            .ToDictionary(p => p.Key, p => p.ToList());

        foreach (var entry in dictionary)

        {

            Console.WriteLine(entry.Key);

            foreach (var package in entry.Value)

            {

                Console.WriteLine($"{package.Company} {package.Weight} {package.TrackingNumber}");

            }

            Console.WriteLine();

        }

    }

}

​

class Package

{

    public string Company { get; set; }

    public double Weight { get; set; }

    public long TrackingNumber { get; set; }

}

​

​