Project Euler Problem #102 in F#: counting triangles that contain the origin












2












$begingroup$


I've recently decided to get into functional programming with F#, and decided to learn the language through Project Euler. The following is my implementation of problem 102:



type Coord = { x: int; y: int }



let origin = { x = 0; y = 0 }



let intToCoord [x; y] = { x = x; y = y }



let twiceTriangleArea a b c =

    abs (a.x * (b.y - c.y) + b.x * (c.y - a.y) + c.x * (a.y - b.y))



let containsOrigin [a; b; c] =

    twiceTriangleArea a b c = twiceTriangleArea origin a b +

        twiceTriangleArea origin b c +

        twiceTriangleArea origin a c



let solution =

    System.IO.File.ReadLines "triangles.txt"

    |> Seq.map (fun line -> 

        line.Split ',' |> Array.map int |> List.ofArray |> List.chunkBySize 2 |> List.map intToCoord

    )

    |> Seq.filter containsOrigin

    |> Seq.length



printfn "%i" solution


While making this, I tried to maintain a functional style as much as possible.



Here is what mainly I want to get from a review:




  1. Is my code idiomatic and functional? Where can it be improved in this regard?

  2. Are there any areas where I am unnecessarily doing extra computation and the code can be simplified?






programming-challenge f# computational-geometry







share|improve this question











$endgroup$

















    2












    $begingroup$


    I've recently decided to get into functional programming with F#, and decided to learn the language through Project Euler. The following is my implementation of problem 102:



    type Coord = { x: int; y: int }
    

    
let origin = { x = 0; y = 0 }
    

    
let intToCoord [x; y] = { x = x; y = y }
    

    
let twiceTriangleArea a b c =
    
    abs (a.x * (b.y - c.y) + b.x * (c.y - a.y) + c.x * (a.y - b.y))
    

    
let containsOrigin [a; b; c] =
    
    twiceTriangleArea a b c = twiceTriangleArea origin a b +
    
        twiceTriangleArea origin b c +
    
        twiceTriangleArea origin a c
    

    
let solution =
    
    System.IO.File.ReadLines "triangles.txt"
    
    |> Seq.map (fun line -> 
    
        line.Split ',' |> Array.map int |> List.ofArray |> List.chunkBySize 2 |> List.map intToCoord
    
    )
    
    |> Seq.filter containsOrigin
    
    |> Seq.length
    

    
printfn "%i" solution


    While making this, I tried to maintain a functional style as much as possible.



    Here is what mainly I want to get from a review:




    1. Is my code idiomatic and functional? Where can it be improved in this regard?

    2. Are there any areas where I am unnecessarily doing extra computation and the code can be simplified?






    programming-challenge f# computational-geometry







    share|improve this question











    $endgroup$















      2












      2








      2





      $begingroup$


      I've recently decided to get into functional programming with F#, and decided to learn the language through Project Euler. The following is my implementation of problem 102:



      type Coord = { x: int; y: int }
      

      
let origin = { x = 0; y = 0 }
      

      
let intToCoord [x; y] = { x = x; y = y }
      

      
let twiceTriangleArea a b c =
      
    abs (a.x * (b.y - c.y) + b.x * (c.y - a.y) + c.x * (a.y - b.y))
      

      
let containsOrigin [a; b; c] =
      
    twiceTriangleArea a b c = twiceTriangleArea origin a b +
      
        twiceTriangleArea origin b c +
      
        twiceTriangleArea origin a c
      

      
let solution =
      
    System.IO.File.ReadLines "triangles.txt"
      
    |> Seq.map (fun line -> 
      
        line.Split ',' |> Array.map int |> List.ofArray |> List.chunkBySize 2 |> List.map intToCoord
      
    )
      
    |> Seq.filter containsOrigin
      
    |> Seq.length
      

      
printfn "%i" solution


      While making this, I tried to maintain a functional style as much as possible.



      Here is what mainly I want to get from a review:




      1. Is my code idiomatic and functional? Where can it be improved in this regard?

      2. Are there any areas where I am unnecessarily doing extra computation and the code can be simplified?






      programming-challenge f# computational-geometry







      share|improve this question











      $endgroup$




      I've recently decided to get into functional programming with F#, and decided to learn the language through Project Euler. The following is my implementation of problem 102:



      type Coord = { x: int; y: int }
      

      
let origin = { x = 0; y = 0 }
      

      
let intToCoord [x; y] = { x = x; y = y }
      

      
let twiceTriangleArea a b c =
      
    abs (a.x * (b.y - c.y) + b.x * (c.y - a.y) + c.x * (a.y - b.y))
      

      
let containsOrigin [a; b; c] =
      
    twiceTriangleArea a b c = twiceTriangleArea origin a b +
      
        twiceTriangleArea origin b c +
      
        twiceTriangleArea origin a c
      

      
let solution =
      
    System.IO.File.ReadLines "triangles.txt"
      
    |> Seq.map (fun line -> 
      
        line.Split ',' |> Array.map int |> List.ofArray |> List.chunkBySize 2 |> List.map intToCoord
      
    )
      
    |> Seq.filter containsOrigin
      
    |> Seq.length
      

      
printfn "%i" solution


      While making this, I tried to maintain a functional style as much as possible.



      Here is what mainly I want to get from a review:




      1. Is my code idiomatic and functional? Where can it be improved in this regard?

      2. Are there any areas where I am unnecessarily doing extra computation and the code can be simplified?






      programming-challenge f# computational-geometry




      programming-challenge f# computational-geometry






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited 1 hour ago







      Arnav Borborah

















      asked 5 hours ago









      Arnav BorborahArnav Borborah

      733221




      733221






















          1 Answer
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          2












          $begingroup$

          It looks OK to me. You can avoid the List.ofArray call, if you change the arguments to intToCoord and containsOrigin to arrays instead of lists:



          let intToCoord [|x; y|] = { x = x; y = y }
          

          
let containsOrigin [|a; b; c|] =
          
    twiceTriangleArea a b c = twiceTriangleArea origin a b +
          
        twiceTriangleArea origin b c +
          
        twiceTriangleArea origin a c
          

          

          

          
let solution =
          
    System.IO.File.ReadLines "p102_triangles.txt"
          
    |> Seq.map (fun line -> 
          
        line.Split ',' |> Array.map int |> Array.chunkBySize 2 |> Array.map intToCoord
          
    )
          
    |> Seq.filter containsOrigin
          
    |> Seq.length





          share|improve this answer









          $endgroup$













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            2












            $begingroup$

            It looks OK to me. You can avoid the List.ofArray call, if you change the arguments to intToCoord and containsOrigin to arrays instead of lists:



            let intToCoord [|x; y|] = { x = x; y = y }
            

            
let containsOrigin [|a; b; c|] =
            
    twiceTriangleArea a b c = twiceTriangleArea origin a b +
            
        twiceTriangleArea origin b c +
            
        twiceTriangleArea origin a c
            

            

            

            
let solution =
            
    System.IO.File.ReadLines "p102_triangles.txt"
            
    |> Seq.map (fun line -> 
            
        line.Split ',' |> Array.map int |> Array.chunkBySize 2 |> Array.map intToCoord
            
    )
            
    |> Seq.filter containsOrigin
            
    |> Seq.length





            share|improve this answer









            $endgroup$


















              2












              $begingroup$

              It looks OK to me. You can avoid the List.ofArray call, if you change the arguments to intToCoord and containsOrigin to arrays instead of lists:



              let intToCoord [|x; y|] = { x = x; y = y }
              

              
let containsOrigin [|a; b; c|] =
              
    twiceTriangleArea a b c = twiceTriangleArea origin a b +
              
        twiceTriangleArea origin b c +
              
        twiceTriangleArea origin a c
              

              

              

              
let solution =
              
    System.IO.File.ReadLines "p102_triangles.txt"
              
    |> Seq.map (fun line -> 
              
        line.Split ',' |> Array.map int |> Array.chunkBySize 2 |> Array.map intToCoord
              
    )
              
    |> Seq.filter containsOrigin
              
    |> Seq.length





              share|improve this answer









              $endgroup$
















                2












                2








                2





                $begingroup$

                It looks OK to me. You can avoid the List.ofArray call, if you change the arguments to intToCoord and containsOrigin to arrays instead of lists:



                let intToCoord [|x; y|] = { x = x; y = y }
                

                
let containsOrigin [|a; b; c|] =
                
    twiceTriangleArea a b c = twiceTriangleArea origin a b +
                
        twiceTriangleArea origin b c +
                
        twiceTriangleArea origin a c
                

                

                

                
let solution =
                
    System.IO.File.ReadLines "p102_triangles.txt"
                
    |> Seq.map (fun line -> 
                
        line.Split ',' |> Array.map int |> Array.chunkBySize 2 |> Array.map intToCoord
                
    )
                
    |> Seq.filter containsOrigin
                
    |> Seq.length





                share|improve this answer









                $endgroup$



                It looks OK to me. You can avoid the List.ofArray call, if you change the arguments to intToCoord and containsOrigin to arrays instead of lists:



                let intToCoord [|x; y|] = { x = x; y = y }
                

                
let containsOrigin [|a; b; c|] =
                
    twiceTriangleArea a b c = twiceTriangleArea origin a b +
                
        twiceTriangleArea origin b c +
                
        twiceTriangleArea origin a c
                

                

                

                
let solution =
                
    System.IO.File.ReadLines "p102_triangles.txt"
                
    |> Seq.map (fun line -> 
                
        line.Split ',' |> Array.map int |> Array.chunkBySize 2 |> Array.map intToCoord
                
    )
                
    |> Seq.filter containsOrigin
                
    |> Seq.length






                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered 3 hours ago









                Henrik HansenHenrik Hansen

                7,87511229




                7,87511229






























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