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ChrisPritchard's solution

to Minesweeper in the F# Track

Published at Aug 26 2018 · 0 comments
Instructions
Test suite
Solution

Add the numbers to a minesweeper board.

Minesweeper is a popular game where the user has to find the mines using numeric hints that indicate how many mines are directly adjacent (horizontally, vertically, diagonally) to a square.

In this exercise you have to create some code that counts the number of mines adjacent to a square and transforms boards like this (where * indicates a mine):

+-----+
| * * |
|  *  |
|  *  |
|     |
+-----+

into this:

+-----+
|1*3*1|
|13*31|
| 2*2 |
| 111 |
+-----+

Running the tests

To run the tests, run the command dotnet test from within the exercise directory.

Further information

For more detailed information about the F# track, including how to get help if you're having trouble, please visit the exercism.io F# language page.

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

MinesweeperTest.fs

// This file was auto-generated based on version 1.1.0 of the canonical data.

module MinesweeperTest

open FsUnit.Xunit
open Xunit

open Minesweeper

[<Fact>]
let ``No rows`` () =
    let minefield: string list = []
    let expected: string list = []
    annotate minefield |> should equal expected

[<Fact(Skip = "Remove to run test")>]
let ``No columns`` () =
    let minefield = [""]
    let expected = [""]
    annotate minefield |> should equal expected

[<Fact(Skip = "Remove to run test")>]
let ``No mines`` () =
    let minefield = 
        [ "   ";
          "   ";
          "   " ]
    let expected = 
        [ "   ";
          "   ";
          "   " ]
    annotate minefield |> should equal expected

[<Fact(Skip = "Remove to run test")>]
let ``Minefield with only mines`` () =
    let minefield = 
        [ "***";
          "***";
          "***" ]
    let expected = 
        [ "***";
          "***";
          "***" ]
    annotate minefield |> should equal expected

[<Fact(Skip = "Remove to run test")>]
let ``Mine surrounded by spaces`` () =
    let minefield = 
        [ "   ";
          " * ";
          "   " ]
    let expected = 
        [ "111";
          "1*1";
          "111" ]
    annotate minefield |> should equal expected

[<Fact(Skip = "Remove to run test")>]
let ``Space surrounded by mines`` () =
    let minefield = 
        [ "***";
          "* *";
          "***" ]
    let expected = 
        [ "***";
          "*8*";
          "***" ]
    annotate minefield |> should equal expected

[<Fact(Skip = "Remove to run test")>]
let ``Horizontal line`` () =
    let minefield = [" * * "]
    let expected = ["1*2*1"]
    annotate minefield |> should equal expected

[<Fact(Skip = "Remove to run test")>]
let ``Horizontal line, mines at edges`` () =
    let minefield = ["*   *"]
    let expected = ["*1 1*"]
    annotate minefield |> should equal expected

[<Fact(Skip = "Remove to run test")>]
let ``Vertical line`` () =
    let minefield = 
        [ " ";
          "*";
          " ";
          "*";
          " " ]
    let expected = 
        [ "1";
          "*";
          "2";
          "*";
          "1" ]
    annotate minefield |> should equal expected

[<Fact(Skip = "Remove to run test")>]
let ``Vertical line, mines at edges`` () =
    let minefield = 
        [ "*";
          " ";
          " ";
          " ";
          "*" ]
    let expected = 
        [ "*";
          "1";
          " ";
          "1";
          "*" ]
    annotate minefield |> should equal expected

[<Fact(Skip = "Remove to run test")>]
let ``Cross`` () =
    let minefield = 
        [ "  *  ";
          "  *  ";
          "*****";
          "  *  ";
          "  *  " ]
    let expected = 
        [ " 2*2 ";
          "25*52";
          "*****";
          "25*52";
          " 2*2 " ]
    annotate minefield |> should equal expected

[<Fact(Skip = "Remove to run test")>]
let ``Large minefield`` () =
    let minefield = 
        [ " *  * ";
          "  *   ";
          "    * ";
          "   * *";
          " *  * ";
          "      " ]
    let expected = 
        [ "1*22*1";
          "12*322";
          " 123*2";
          "112*4*";
          "1*22*2";
          "111111" ]
    annotate minefield |> should equal expected
module Minesweeper
open System

let annotate (input: string list) = 
    let minesAndAdjancies = 
        let adjacencies point =
            [-1..1] |> List.collect (fun y -> [-1..1] |> List.map (fun x -> (fst point + y, snd point + x)))
            |> List.except [point]
        let forPoint y x c = if c = '*' then ((y,x), adjacencies (y,x) |> Some) else (((y,x)), None)
        input 
            |> List.mapi (fun y line -> line |> Seq.toList |> List.mapi (fun x c -> forPoint y x c))
            |> List.concat |> List.filter (fun (_,a) -> a.IsSome) |> List.map (fun (p,a) -> (p,a.Value))
    let plotter y x c = 
        if c = '*' then '*' else 
            let count = List.filter (fun (_,a) -> List.contains (y,x) a) minesAndAdjancies |> List.length
            if count = 0 then ' ' else count |> string |> char
    input 
        |> List.mapi (fun y line -> line |> Seq.toList |> List.mapi (fun x c -> plotter y x c) |> String.Concat)

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