Place tiles in circular fashion

Question

I need to place tiles in this fashion:

I only need the logic, so language doesn't matter.Thank you!

The number of tiles is unknown!

This is how far I got:

var setX = 0;
var setY = 0;
var count = 0;
$(".pic").each(function() 
{ 
   // set setX and setX based on count 
   $(this).animate({"left":setX,"top":setY},2000) 
   count++
});

Answer 1

Some implementation in C#:

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

public class Program
{

    public struct Pair
    {
        int X;
        int Y;
        public Pair( int X, int Y )
        {
            this.X = X;
            this.Y = Y;
        }
        public override string ToString()
        {
            return String.Format( "({0},{1})", X, Y );
        }
    }

    public static IEnumerable<Pair> Positions( int StartX, int StartY )
    {
        int[] DeltaX = { 0, 1, 0,-1 };
        int[] DeltaY = { 1, 0,-1, 0 };

        int Direction = 1;

        int X = StartX;
        int Y = StartY;

        int Left = StartX;
        int Right = StartX;
        int Top = StartY;
        int Bottom = StartY;

        yield return new Pair(X, Y);

        while ( true )
        {
            switch ( Direction )
            {
            case 0:
                Top += 1;
                while ( Y < Top )
                {
                    X += DeltaX[Direction];
                    Y += DeltaY[Direction];
                    yield return new Pair( X, Y );
                }
                break;
            case 1:
                Right += 1;
                while ( X < Right )
                {
                    X += DeltaX[Direction];
                    Y += DeltaY[Direction];
                    yield return new Pair( X, Y );
                }
                break;
            case 2:
                Bottom -= 1;
                while ( Y > Bottom )
                {
                    X += DeltaX[Direction];
                    Y += DeltaY[Direction];
                    yield return new Pair( X, Y );
                }
                break;
            case 3:
                Left -= 1;
                while ( X > Left )
                {
                    X += DeltaX[Direction];
                    Y += DeltaY[Direction];
                    yield return new Pair( X, Y );
                }
                break;
            default:
                break;
            }

            Direction++;
            Direction %= 4;
        }
    }

    public static void Main()
    {
        var Coords = Positions( 10, 10 ).Take( 15 );
        foreach ( Pair iPair in Coords )
        {
            Console.WriteLine( iPair.ToString() );
        }
        Console.ReadKey();
    }
}