Data commit

Task/100-prisoners/F-Sharp/100-prisoners.fs

@@ -0,0 +1,37 @@
+let rnd = System.Random()
+let shuffled min max =
+    [|min..max|] |> Array.sortBy (fun _ -> rnd.Next(min,max+1))
+
+let drawers () = shuffled 1 100
+
+// strategy randomizing drawer opening
+let badChoices (drawers' : int array) =
+    Seq.init 100 (fun _ -> shuffled 1 100 |> Array.take 50) // selections for each prisoner
+    |> Seq.map (fun indexes -> indexes |> Array.map(fun index -> drawers'.[index-1])) // transform to cards
+    |> Seq.mapi (fun i cards -> cards |> Array.contains i) // check if any card matches prisoner number
+    |> Seq.contains false // true means not all prisoners got their cards
+let outcomeOfRandom runs =
+    let pardons = Seq.init runs (fun _ -> badChoices (drawers ()))
+                  |> Seq.sumBy (fun badChoice -> if badChoice |> not then 1.0 else 0.0)
+    pardons/ float runs
+
+// strategy optimizing drawer opening
+let smartChoice max prisoner (drawers' : int array) =
+    prisoner
+    |> Seq.unfold (fun selection ->
+        let card = drawers'.[selection-1]
+        Some (card, card))
+    |> Seq.take max
+    |> Seq.contains prisoner
+let smartChoices (drawers' : int array) =
+    seq { 1..100 }
+    |> Seq.map (fun prisoner -> smartChoice 50 prisoner drawers')
+    |> Seq.filter (fun result -> result |> not) // remove all but false results
+    |> Seq.isEmpty // empty means all prisoners got their cards
+let outcomeOfOptimize runs =
+    let pardons = Seq.init runs (fun _ -> smartChoices (drawers()))
+                  |> Seq.sumBy (fun smartChoice' -> if smartChoice' then 1.0 else 0.0)
+    pardons/ float runs
+
+printfn $"Using Random Strategy: {(outcomeOfRandom 20000):p2}"
+printfn $"Using Optimum Strategy: {(outcomeOfOptimize 20000):p2}"