ProgramGood.Net - Git

Euler 15–How Many Routes in a 20 by 20 Grid

Dave Mateer — Tue, 05 Jun 2012 16:50:27 GMT

Am trying out using git now on every project - mainly so I can easily revert if I mess things up. Good practice.

git init

git add .

git commit -m "first commit of Euler 15"

git checkout -b firsttry

git branch (to see branches)

gitgui

R# – Move to another file with same name

Forumla

http://locationcube.blogspot.co.uk/2010/12/project-eulerproblem-15.html

The formula is n! / r! (n-r)!

Where n is 40 and r is 20… so 40!/(20! * 20!)

Which gives us: 137846528820 ways to get there!

In fact Google’s online calculator can do this for you….

Just type 40 choose 20 into Google!!

Discrete Mathematics

– on a 2*2 square it takes 4 steps to reach the end. So on a 20*20 square it takes 40 steps.

20 increases in x and 20 increases in y

how many different ways can you choose 20 elements out of a set of 40 elements.

We can use a formula to solve this. “n choose r formula”: N!/r!(n-r)

40!/((20!)(40-20)!)

N = number of elements (40)

r = how many we want to choose

137,846,528,820

Dynamic Programming

How many routes are there through a 20×20 grid? or.. total number of ways to arrive at a node?

dynamic programming is a method for solving complex problems by breaking them down into simpler subproblems

We find the total number of ways to arrive at a node:

“Sum of the count from above and to the left”

[TestFixture]

public class DynamicProgrammingTests

{

private DynamicProgramming dynamicProgramming;

[SetUp]

public void DoFirst()

{

this.dynamicProgramming = new DynamicProgramming();

}

[Test]

public void Four_DynamicProgrammingSolver_GivesAnswerOf70()

{

var result = dynamicProgramming.Solve(4);

Assert.AreEqual(70, result);

}

[Test]

public void Five_DynamicProgrammingSolver_GivesAnswerOf252()

{

var result = dynamicProgramming.Solve(5);

Assert.AreEqual(252, result);

}

[Test]

public void Twenty_DynamicProgrammingSolver_GivesAnswerOf252()

{

var result = dynamicProgramming.Solve(20);

//137,846,528,820

Assert.AreEqual(137846528820, result);

}

}

//using property of problem that

//total number of ways to arrive at a node

//is count from left and above

//so we build an array with total number of ways to arrive
at a node

public class DynamicProgramming

{

public double Solve(int sizeOfGrid)

{

var array = new double[sizeOfGrid+2,
sizeOfGrid+2];

int i, j;

array[1, 1] = 1;

for (i = 1; i <= sizeOfGrid+1; i++)

{

for (j = 1; j <= sizeOfGrid+1; j++)

{

//count from left, then count from above

array[i, j] += array[i - 1, j] + array[i, j - 1];

}

}

double result = array[sizeOfGrid+1, sizeOfGrid+1];

return result;

}

}

put in photo here of array with answers in it.

Brute Force – Recursive

[TestFixture]

public class SolverTests

{

private BruteForceRecursionSolver bruteForceRecursionSolver;

[SetUp]

public void DoThisAtStart()

{

this.bruteForceRecursionSolver = new BruteForceRecursionSolver();

}

[Test]

public void TwoGivesAnswerOf6()

{

bruteForceRecursionSolver.gridSize = 2;

var result = bruteForceRecursionSolver.Progress(0,
0);

Assert.AreEqual(6, result);

}

[Test]

public void ThreeGivesAnswerOf20()

{

bruteForceRecursionSolver.gridSize = 3;

var result = bruteForceRecursionSolver.Progress(0,
0);

Assert.AreEqual(20, result);

}

[Test]

public void FourGivesAnswerOf70()

{

bruteForceRecursionSolver.gridSize = 4;

var result = bruteForceRecursionSolver.Progress(0,
0);

Assert.AreEqual(70, result);

}

[Test]

public void FiveGivesAnswerOf252()

{

bruteForceRecursionSolver.gridSize = 5;

var result = bruteForceRecursionSolver.Progress(0,
0);

Assert.AreEqual(252, result);

}

[Test]

public void TenGivesAnswerOf184756()

{

bruteForceRecursionSolver.gridSize = 10;

var result = bruteForceRecursionSolver.Progress(0,
0);

Assert.AreEqual(184756, result);

}

[Test]

public void ElevenGivesAnswerOf705432()

{

bruteForceRecursionSolver.gridSize = 11;

var result = bruteForceRecursionSolver.Progress(0,
0);

Assert.AreEqual(705432, result);

}

}

//http://stackoverflow.com/questions/2200236/project-euler-15

public class BruteForceRecursionSolver

{

public int gridSize;

// top left is 0,0

public int Progress(int x, int y)

{

int i = 0;

if (x < gridSize)

//favours going right

i += Progress(x + 1, y);

if (y < gridSize)

i += Progress(x, y + 1);

//reached bottom right

if (x == gridSize && y == gridSize)

return 1;

return i;

}

}

This is very much brute force..

This took about 1.5 hours:

public class SolveRecursion

{

public long Combination
= 0;

public int GridSize;

public void CalculateCombination(int x
= 0, int y = 0)

{

if (x < GridSize)

{

CalculateCombination(x + 1, y);

}

if (y < GridSize)

{

CalculateCombination(x, y + 1);

}

if (x == GridSize && y == GridSize)

Combination++;

}

}

static void Main(string[]
args)

{

//gives correct answer: 137,846,528,820

Console.WriteLine("starting");

Stopwatch stopWatch = new Stopwatch();

stopWatch.Start();

var solveRecursion2 = new SolveRecursion {
GridSize = 20 };

solveRecursion2.CalculateCombination();

var result = solveRecursion2.Combination;

stopWatch.Stop();

TimeSpan ts = stopWatch.Elapsed;

Console.WriteLine("Result
is: {0}, time
was {1} seconds",
result, ts.ToString());

}

and non recursive thoughts on:

http://stackoverflow.com/questions/10890516/rewrite-recursive-algorithm-more-simply-euler-15

GitHub–permission denied publickey

Dave Mateer — Tue, 25 Oct 2011 22:26:51 GMT

hmmmm

I did all this (using an existing repo)

follow instructions here!

http://help.github.com/win-set-up-git/

VidPub 2 – Remove ASP.NET Membership, Massive test against DB

Dave Mateer — Wed, 21 Sep 2011 04:16:27 GMT

Custom Membership..forms.

Don’t advocate roll own membership

ASP.NET Membership works if

SQL Server forever
Forms auth
Can login multiple times

OpenID

TDD/BDD do this.

NUnit
TestDriven.net

Code Snippets

To help with mundane writing code in unit tests.

Ctrl K Ctrl B

http://weblogs.asp.net/kdente/archive/2005/05/05/405843.aspx Kevin Dentes Blogs and nunit snippets **not imported yet as wasn’t in .snippet format

Libraries\Documents\Visual Studio 2010\Code Snippets\Visual C#\My Code Snippets

Git console in VS

Tools/External menu.

which then appears in the Tools menu as git. Change to &g for keyboard accelerator.

Feature branch in Git

Master is for finalised and deployed (?) code

git branch (to see current branches)

git checkout –b membership

.gitignore


*resharper.user


[Dd]ebug/


[Rr]elease/


build/


[Bb]in/


[Oo]bj/


*.suo


*.sln.cache


_ReSharper.*/


*.user

git add .

Global GitIgnore

http://jqr.github.com/2009/02/03/global-git-ignore.html

git config –global core.excludesfile c:/dev/Global.gitignore

Test 1 – Not Accept Email with < 6 Chars

From http://weblogs.asp.net/nunitaddin/

Alt + T reassigned for run tests in TestDriven.Net

Alt + D run tests in debug

Code
Snippet
 public class TestBase {

 public void Describes(string description)
{

 Console.WriteLine("-------------------------------");

 Console.WriteLine(description);

 Console.WriteLine("-------------------------------");

 }

 public void isPending()
{

 Console.WriteLine(GetCaller() + "
-- PENDING --");

 Assert.Inconclusive();

 }

 public string GetCaller()
{

 StackTrace stack = new StackTrace();

 return stack.GetFrame(2).GetMethod().Name.Replace("_", "
");

 }

 }

So can get a bit of nice debug in output window:

YAGNI – writing smallest amount of code to make test pass.. weird but good.

Code
Snippet
[TestFixture]

 public class MembershipSpecs : TestBase{

 public MembershipSpecs()
{

 this.Describes("User
Registration");

 }

 [Test]

 public void registration_should_not_accept_email_with_lt_6_chars()
{

 var membership = new Membership();

 var result = membership.Register("test@test.com", "password", "password");

 Assert.False(result.Success);

 }

 }

and simplest possible implementation (not really, but Rob has an end in mind)

used Ctrl . in VS to make Membership class and file, and method.

Code
Snippet
public class Membership {

 public dynamic Register(string email, string password, string confirm)
{

 dynamic result = new ExpandoObject();

 result.Success = false;

 return result;

 }

 }

Code
Snippet
[Test]

public void registration_should_not_accept_email_with_lt_6_chars()
{

var result = _membership.Register("e", "password", "password");

Assert.False(result.Success);

}

[Test]

public void registration_should_not_accept_password_with_lt_6_chars()
{

var result = _membership.Register("test@test.com", "x", "x");

Assert.False(result.Success);

}

[Test]

public void registration_should_not_accept_mismatched_passwords()
{

var result = _membership.Register("test@test.com", "password1", "password2");

Assert.False(result.Success);

}

testing the False cases

Code
Snippet
public dynamic Register(string email, string password, string confirm)
{

dynamic result = new ExpandoObject();

result.Success = false;

if (email.Length >= 6 && password.Length >=6 && password.Equals(confirm))

result.Success = true;

return result;

}

Persist Information to DB – Massive

http://blog.wekeroad.com/helpy-stuff/and-i-shall-call-it-massive

Rails doesn’t matter to goto db..can be fast enough.

SQL CE4 in App_Data in Test project. **This didn’t work.. am using SQL Server**

Seed on ID the PK. getdate() on 3 date fields as default.

How to persist data? Simplest possible for now is Massive.. a Dynamic ORM in 500lines or do.

https://github.com/robconery/massive

Test 2 – Registration Should Not Accept Duplicate Emails

Test is something like:

[Test]

 public void registration_should_not_accept_duplicate_emails()
{

 var result = _membership.Register("test@test.com", "password", "password");

 var result2 = _membership.Register("test@test.com", "password", "password");

 Assert.False(result2.Success);

 }

so need persistence to test this:

Going to clean the db before each test!

Massive works by translating the properties of the anonymous object into column names:

Problem: Couldn’t get Massive to connect to SQLServerCompact4.0 database with connection string:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>   <connectionStrings>     <add name="Membership"      connectionString="Data Source=C:\Dev\VidPub\Source\VidPub.Tests\App_Data\Membership_Test.sdf"      providerName="System.Data.SqlServerCE.4.0" />   </connectionStrings>
</configuration>

installed classic 2000 Northwind sample:

http://www.microsoft.com/download/en/confirmation.aspx?id=23654 then look in C:\SQL Server 2000 Sample Databases

http://ndc2011.macsimum.no/mp4/Day2%20Thursday/Track1%201140-1240.mp4 – Interesting talk from Norway on Data access history.

Now I can get a console App to talk to SQL Server Compact 4.0 :

string connectionString = ConfigurationManager.ConnectionStrings["southwind"].ConnectionString;

 //SqlCeConnection
connection = new SqlCeConnection(@"Data Source=SouthWind.sdf");

 SqlCeConnection connection = new SqlCeConnection(connectionString);

 SqlCeCommand command = new SqlCeCommand("SELECT
* FROM People", connection);

 SqlCeDataAdapter dataAdapter = new SqlCeDataAdapter(command);

 DataSet ds = new DataSet();

 dataAdapter.Fill(ds);

 Console.WriteLine(ds.GetXml());

now I need to get Massive talking to that db.

I can kind of get it working by changing the _providerName to

            var _providerName = "System.Data.SqlServerCE.4.0";

https://github.com/robconery/massive/pull/65 here is a fix by pulling from the App.config.

Getting strange errors!

Reverting to SQL Server

<configuration>

 <connectionStrings>

 <!--<add name="Membership"
providerName="System.Data.SqlServerCE.4.0" connectionString="Data Source=C:\Dev\VidPub\Source\VidPub.Tests\Membership_Test.sdf"
/>-->

 <add name="Membership" providerName="System.Data.SqlClient" connectionString="Data
Source=.\;Initial Catalog=Membership_Test;Integrated Security=SSPI;" />

 </connectionStrings>

</configuration>

and change provider name back to:

var _providerName = "System.Data.SqlClient";

and to put a unique constrant on SQL Server column: http://stackoverflow.com/questions/64981/sql-server-2005-how-create-a-unique-constraint

Code Snippets

testn is setup for me to produce:

 [Test]         public void MyTestMethod() {                      }

VidPub1–Setting up Solution

Dave Mateer — Tue, 20 Sep 2011 01:30:54 GMT

Notes from TekPub ASP.NET MVC3 series of tutorials.

Startup – big idea.. charge people money for
Good idea, well executed
Get site out there and pay the bills!

Why MVC3 in this Fast Paced Startup?

Good stable version of MVC
I know C#

What are we doing (Elevator pitch) and when are we going to do it?

1 sentence!

Platform and Tools

MVC3

Unfuddle for project mgt

or agilezen (kanban)

Source is on http://github.com/tekpub/mvc3

Setup a new MVC3 solution called VidPub.Web

Lib is for external dlls. Docs are for docs. Everything is under git

git init in \dev\VidPub

git add .

git commit –am “Initial load”

DropBox

mkdir e:\dropbox\repositories\vpub

in e:\dropbox\repositories\vpub

git init –bare

from \dev folder git push origin master

So other people can then pull from that repository… it is the whole repo up there, not just source.

Test Project

Have just created a container.

Authentication

Don’t want concurrent authentcation.. ie users sharing accounts. Could use token based.

Now, 1 Year, 3 Years

ASP.NET Membership – complicated..

Consistency of FileNames

Public\javscripts

Public\stylesheets

no more content directory

Model\AccountModels.cs to AccountModel

change CSS path in _Layout.cshtml

CDN

http://code.google.com/apis/libraries/devguide.html#jquery

make faster for user as they may have this cached in their browser. Also save us a bit of bandwidth. Cache up to a year.

If using Azure to host http://www.microsoft.com/windowsazure/msdn-benefits/ MSDN have got some benefits.

Logging

NLog using NuGet

Code
Snippet
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >

 <targets>

 <!--Useful for
debugging-->

 <target name="console" xsi:type="ColoredConsole"

 layout="${date:format=HH\:mm\:ss}|${level}|${stacktrace}|${message}" />

 <target name="file" xsi:type="File" fileName="${basedir}/App_Data//logs/site.log"

 layout="${date}:
${message}" />

 <target name="eventlog" xsi:type="EventLog" source="My
App" log="Application"

 layout="${date}:
${message} ${stacktrace}" />

 </targets>

 <rules>

 <logger name="*" minlevel="Info" writeTo="file" />

 <logger name="*" minlevel="Fatal" writeTo="eventlog" />

 </rules>

</nlog>

in dev we’re going to log everything to a file in App_Data/logs

In \Infrastructure we’ve got some code to help us log with an interface extracted.

Code
Snippet
 public class NLogger :
VidPub.Web.Infrastructure.Logging.ILogger {

 Logger _logger;

 public NLogger()
{

 _logger = LogManager.GetCurrentClassLogger();

 }

 public void LogInfo(string message)
{

 _logger.Info(message);

 }

 public void LogWarning(string message)
{

 _logger.Warn(message);

 }

 public void LogDebug(string message)
{

 _logger.Debug(message);

 }

 public void LogError(string message)
{

 _logger.Error(message);

 }

 public void LogError(Exception x)
{

 LogError(BuildExceptionMessage(x));

 }

 public void LogFatal(string message)
{

 _logger.Fatal(message);

 }

 public void LogFatal(Exception x)
{

 LogFatal(BuildExceptionMessage(x));

 }

 string BuildExceptionMessage(Exception x)
{

 Exception logException = x;

 if (x.InnerException != null)

 logException = x.InnerException;

 string strErrorMsg = Environment.NewLine + "Error
in Path :" + System.Web.HttpContext.Current.Request.Path;

 // Get the QueryString
along with the Virtual Path

 strErrorMsg += Environment.NewLine + "Raw
Url :" + System.Web.HttpContext.Current.Request.RawUrl;

 // Get the error message

 strErrorMsg += Environment.NewLine + "Message
:" + logException.Message;

 // Source of the message

 strErrorMsg += Environment.NewLine + "Source
:" + logException.Source;

 // Stack Trace of
the error

 strErrorMsg += Environment.NewLine + "Stack
Trace :" + logException.StackTrace;

 // Method where the
error occurred

 strErrorMsg += Environment.NewLine + "TargetSite
:" + logException.TargetSite;

 return strErrorMsg;

 }

 }

IoC

So we don’t have anything coupled tightly right from the start (eg logging which we’re doing next).. lets use IoC

Ninject.MVC3

Wire up in global.asax

 public class MvcApplication : NinjectHttpApplication  {

**NO this is not correct as in MVC3 it is bootstrapped, so just leave as:

public class MvcApplication : System.Web.HttpApplication {

Setting up logging in App_Start bootstrapper file.

“Every time you see a request for ILogger interface in a controller, return a new NLogger class”

kernel.Bind<ILogger>().To<NLogger>();

added in Logs/Site.log into our project.

Glimpse

Added in bookmarks into bar to turn on and off.

git add .

git commit –am “Added logging, IoC and rearranged stuff”

git push origin master (to save to dropbox)

current state of play of our filesystem.