Data commit

Task/Rep-string/F-Sharp/rep-string.fs

@@ -0,0 +1,35 @@
+let isPrefix p (s : string) = s.StartsWith(p)
+let getPrefix n (s : string) = s.Substring(0,n)
+
+let repPrefixOf str =
+    let rec isRepeatedPrefix p s =
+        if isPrefix p s then isRepeatedPrefix p (s.Substring (p.Length))
+        else isPrefix s p
+
+    let rec getLongestRepeatedPrefix n =
+        if n = 0 then None
+        elif isRepeatedPrefix (getPrefix n str) str then Some(getPrefix n str)
+        else getLongestRepeatedPrefix (n-1)
+
+    getLongestRepeatedPrefix (str.Length/2)
+
+[<EntryPoint>]
+let main argv =
+    printfn "Testing for rep-string (and showing the longest repeated prefix in case):"
+    [
+    "1001110011"
+    "1110111011"
+    "0010010010"
+    "1010101010"
+    "1111111111"
+    "0100101101"
+    "0100100"
+    "101"
+    "11"
+    "00"
+    "1"
+    ] |>
+    List.map (fun s ->
+        match repPrefixOf s with | None -> s + ": NO" | Some(p) -> s + ": YES ("+ p + ")")
+    |> List.iter (printfn "%s")
+    0