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c#expression-trees

Expression Trees for Grade School puzzle

I am trying to learn Expression Trees in C#. Can someone help me solve this puzzle found in Math Logic Puzzles by Kurt Smith ISBN 0-8069-3864-1 in C# code using Expression Trees link to First Printing Edition? Or, could it be, that this puzzle is best suited for a different approach? Am I trying to put a slipper on an Elephants foot? enter image description here

Here is the code I have so far

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

namespace ExpTreesBasics1
{
class Program
{

    List<Person> ListOfPersons = new List<Person>(); 

    static void Main(string[] args)
    {
        Person _paul = new Person()
        {
            Mountain = new Mountain(),
            Pack = new Pack() { WeightExpression = Expression.Constant(30) }
        };

        Person _daleDorsey = new Person() {Mountain = null, Pack = new Pack() {Weight = 0}};

        Person _jimMcGee = new Person() {Mountain = null, Pack = new Pack() {Weight = 0}};

         Person _geraldBrown = new Person()
         {
             Mountain = new Mountain() {Height = 124},
             Pack = new Pack() { WeightExpression = Expression.Subtract(Expression.Constant(_daleDorsey.Pack.Weight), Expression.Constant(_jimMcGee.Pack.Weight)) }
         };

         Person _andyStiller = new Person()
         {
             Mountain = new Mountain()
             {
                 HeightExpression = Expression.Add(Expression.Constant(865), Expression.Constant(_geraldBrown.Mountain.Height))
             },
             Pack = new Pack() {  WeightExpression  = Expression.Divide(.5, Expression.Lambda(Person))}
         };



        var result = Expression.Add(Expression.Constant(865), Expression.Constant(_geraldBrown.Mountain.Height));

    }
}

public class Person
{
    public Mountain Mountain { get; set; }
    public Pack Pack { get; set; }
}

public class Mountain
{
    public string Name { get; set; }
    public int Height { get; set; }
    public Expression HeightExpression { get; set; }
}

public class Pack
{
    public int Weight { get; set; }
    public Expression WeightExpression { get; set; }
}

}

Solution

  • Here's a brute force solution in F#. Not sure this is really the best way of doing it - it works here because the set of combinations of first name / last name / weight / mountain is relatively small (about 1.7m permutations) - but at least it works :)

    Posted as a gist because it's a reasonably large code snippet.

    https://gist.github.com/isaacabraham/7a4c1a9beba5bb9fd9e0