John
Friday, February 27, 2009 @ 07:45
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Summary EulerWell is a simple framework for solving Project Euler problems.
Project Euler is a collection of challenging math and programming puzzles. As the site itself says,
Project Euler is a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve. Although mathematics will help you arrive at elegant and efficient methods, the use of a computer and programming skills will be required to solve most problems.
After talking with some colleagues, I thought it might be useful to start walking through some of these problems as exercises in writing some fun and useful C#. This isn't a new idea, of course -- the natural appeal of writing code to solve simple problems in interesting ways has broad appeal. For example, PyEuler tries to accomplish the same thing by using a functional-programming style of Python.
To accomplish this, I wrote a lightweight framework called EulerWell. EulerWell lets you:
- Have a common framework to implement solutions to Project Euler problems.
- Run unit tests for each problem to prove that it works correctly and produces the desired result.
- Reuse previously solved problems to understand how to solve more complex ones.
The last point is worth noting. Software has many parallels to math here: if you can reduce a complex problem to its more easily solvable constituents, you have to do much less work than solving the problem head-on. We'll see later on that this proves to be a crucial factor in how difficult Project Euler problems appear to be at first glance.
I've opened a Git repository for EulerWell here. You can clone the repository with the following git command.
git clone git://github.com/fj/euler-well.git
Overview of EulerWell
EulerWell is divided into three projects:
EulerWell.Commoncontains a simple framework to describe Project Euler problems.EulerWell.Solverscontains implementations of solutions to Project Euler problems.EulerWell.Testscontains unit tests that you can run against the solution implementations to verify their correctness.
EulerWell.Common namespace
EulerWell.Common is simple and straightforward, and contains only three entities.
- The
SolutionStrategy<T>delegate represents an implementation of the solution to a particular Project Euler problem. The type parameter indicates the type of value that will be returned as an answer. Typically this is a numeric value.
namespace DistilledB.EulerWell.Common {
public delegate T SolutionStrategy<T>();
}- The
IProblemSolver<T>interface represents an implementation of the solution to a particular Project Euler problem. Each of theSolutionStrategy<T>instances inStrategiesis capable of solving the problem.
using System.Collections.Generic;
namespace DistilledB.EulerWell.Common {
public interface IProblemSolver<T> {
IEnumerable<SolutionStrategy<T>> Strategies { get; }
}
}- Finally, the
ProjectEulerProblemAttributeassociates metadata about the Project Euler problem with a particularIProblemSolver<T>. There's nothing that prevents you from using this attribute on other things affiliated with a particular Project Euler problem, however.
using System;
namespace DistilledB.EulerWell.Common {
[AttributeUsage(AttributeTargets.Class)]
public class ProjectEulerProblemAttribute : Attribute {
public string Name { get; set; }
public string Id { get; set; }
public string Description { get; set; }
}
}EulerWell.Solvers and EulerWell.Tests namespaces
These two parts represent the meat of the implementation here. EulerWell.Solvers contains each implementation of a solution to a problem, while EulerWell.Tests contains tests that apply to each one.
In an upcoming post we'll talk about how to solve Project Euler problems of varying difficulty.
