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  1. open System
  2. open System.IO
  3.  
  4. type Direction = UP | DOWN | LEFT | RIGHT
  5.  
  6. let rec fillSpiral (spiral:int[,]) num square goal curX curY direction =
  7.     match num with
  8.     | x when num=goal+1 -> spiral
  9.     | _ -> 
  10.            spiral.[curX,curY] <- num
  11.            let newDirection = match direction with
  12.                               | UP -> match curY with
  13.                                       | a when curY=0 -> RIGHT
  14.                                       | b when spiral.[curX,(curY-1)] <> -1 -> RIGHT
  15.                                       | _ -> UP
  16.                               | DOWN -> match curY with
  17.                                         | a when curY=square-1 -> LEFT
  18.                                         | b when spiral.[curX,(curY+1)] <> -1 -> LEFT
  19.                                         | _ -> DOWN
  20.                               | LEFT -> match curX with
  21.                                         | a when curX=0 -> UP
  22.                                         | b when spiral.[curX-1,curY] <> -1 -> UP
  23.                                         | _ -> LEFT
  24.                               | RIGHT -> match curX with
  25.                                          | a when curX=square-1 -> DOWN
  26.                                          | b when spiral.[curX+1,curY] <> -1 -> DOWN
  27.                                          | _ -> RIGHT
  28.            let nextX = match newDirection with
  29.                        | LEFT -> curX-1
  30.                        | RIGHT -> curX+1
  31.                        | _ -> curX
  32.            let nextY = match newDirection with
  33.                        | UP -> curY-1
  34.                        | DOWN -> curY+1
  35.                        | _ -> curY
  36.            fillSpiral spiral (num+1) square goal nextX nextY newDirection
  37.  
  38. let makeSpiral num =
  39.     let square = num*num
  40.     let matrix = Array2D.init num num (fun x y -> -1)
  41.     let spiral = fillSpiral matrix 1 num square 0 0 RIGHT
  42.     let alignment = ((log (square |> double))) |> int
  43.     for y in [0..num-1] do
  44.         for x in [0..num-1] do
  45.             printf "%*d " alignment spiral.[x,y]
  46.         printfn ""
  47.     ()
  48.  
  49. [<EntryPoint>]
  50. let main argv = 
  51.     makeSpiral 4
  52.     printfn ""
  53.     makeSpiral 5
  54.     0
Success #stdin #stdout 0.02s 132800KB
comments ()
stdin 
Standard input is empty
stdout 
 1  2  3  4 
12 13 14  5 
11 16 15  6 
10  9  8  7 

  1   2   3   4   5 
 16  17  18  19   6 
 15  24  25  20   7 
 14  23  22  21   8 
 13  12  11  10   9
https://ideone.com/GWJ59g
language:
F# (mono 4.1)
created:
7 years ago
visibility:
public

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