Data commit

Task/Knuth-shuffle/F-Sharp/knuth-shuffle-1.fs

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+open System
+
+let FisherYatesShuffle (initialList : array<'a>) =                  // '
+    let availableFlags = Array.init initialList.Length (fun i -> (i, true))
+                                                                    // Which items are available and their indices
+    let rnd = new Random()
+    let nextItem nLeft =
+        let nItem = rnd.Next(0, nLeft)                              // Index out of available items
+        let index =                                                 // Index in original deck
+            availableFlags                                          // Go through available array
+            |> Seq.filter (fun (ndx,f) -> f)                        // and pick out only the available tuples
+            |> Seq.nth nItem                                        // Get the one at our chosen index
+            |> fst                                                  // and retrieve it's index into the original array
+        availableFlags.[index] <- (index, false)                    // Mark that index as unavailable
+        initialList.[index]                                         // and return the original item
+    seq {(initialList.Length) .. -1 .. 1}                           // Going from the length of the list down to 1
+    |> Seq.map (fun i -> nextItem i)                                // yield the next item

Task/Knuth-shuffle/F-Sharp/knuth-shuffle-2.fs

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+let KnuthShuffle (lst : array<'a>) =                   // '
+    let Swap i j =                                                  // Standard swap
+        let item = lst.[i]
+        lst.[i] <- lst.[j]
+        lst.[j] <- item
+    let rnd = new Random()
+    let ln = lst.Length
+    [0..(ln - 2)]                                                   // For all indices except the last
+    |> Seq.iter (fun i -> Swap i (rnd.Next(i, ln)))                 // swap th item at the index with a random one following it (or itself)
+    lst                                                             // Return the list shuffled in place

Task/Knuth-shuffle/F-Sharp/knuth-shuffle-3.fs

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+> KnuthShuffle [| "Darrell"; "Marvin"; "Doug"; "Greg"; "Sam"; "Ken" |];;
+val it : string array = [|"Marvin"; "Doug"; "Sam"; "Darrell"; "Ken"; "Greg"|]