using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var dict = new Dictionary<Point, int>();

        for(var i = 100; i >= 0; i--)

        {

            for(var j = 100; j >= 0; j--)

            {

                dict.Add(new Point {X = j, Y = i}, i);

            }

        }

​

        foreach(var kvp in dict)

            Console.WriteLine(kvp.Key);

        Console.WriteLine("After sorting:");

​

        dict = dict.OrderBy(x => x.Key.X)

            .ThenBy(x => x.Key.Y)

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

​

        foreach (var kvp in dict)

            Console.WriteLine(kvp.Key);

    }

}

​

public class Point

{

    public double X { get; set; }

    public double Y { get; set; }

    public override string ToString()

    {

        return string.Format("X = {0}, Y = {1}", X, Y);

    }

}