initial commit

14.fs

@@ -0,0 +1,15 @@
+module _14
+
+let collatzConjecture n =
+    match n with
+        | 0L -> None
+        | 1L -> Some(1L,0L)
+        | n -> Some(n,
+                    if n % 2L = 0L then n/2L
+                    else if n % 2L = 1L then 3L*n + 1L
+                    else 1L)
+
+let getLongestChain =
+    [1L..1000000L]
+        |> Seq.map (fun i -> (i |> Seq.unfold collatzConjecture |> Seq.length, i))
+        |> Seq.max