Merge remote-tracking branch 'mortenaa/CollatzConjecture'

config.json

@@ -322,6 +322,16 @@
 
       ]
     },
+    {
+      "uuid": "1f52ab74-02d5-db80-8f95-521aba04d183e704422",
+      "slug": "collatz-conjecture",
+      "core": false,
+      "unlocked_by": null,
+      "difficulty": 1,
+      "topics": [
+
+      ]
+    },
     {
       "uuid": "a730ca85-057d-db80-e44e-25b8028acede6337cca",
       "slug": "pascals-triangle",

exercises/collatz-conjecture/CollatzConjecture.elm

@@ -0,0 +1,2 @@
+module CollatzConjecture exposing (..)
+

exercises/collatz-conjecture/CollatzConjecture.example.elm

@@ -0,0 +1,19 @@
+module CollatzConjecture exposing (collatz)
+
+
+collatz : Int -> Result String Int
+collatz start =
+    if start <= 0 then
+        Err "Only positive numbers are allowed"
+    else
+        Ok (collatzHelper 0 start)
+
+
+collatzHelper : Int -> Int -> Int
+collatzHelper steps start =
+    if start == 1 then
+        steps
+    else if start % 2 == 0 then
+        collatzHelper (1 + steps) (start // 2)
+    else
+        collatzHelper (1 + steps) (3 * start + 1)

exercises/collatz-conjecture/elm-package.json

@@ -0,0 +1,15 @@
+{
+    "version": "3.0.0",
+    "summary": "Exercism problems in Elm.",
+    "repository": "https://github.com/exercism/elm.git",
+    "license": "BSD3",
+    "source-directories": [
+        "."
+    ],
+    "exposed-modules": [],
+    "dependencies": {
+        "elm-lang/core": "5.0.0 <= v < 6.0.0"
+    },
+    "elm-version": "0.18.0 <= v < 0.19.0"
+}
+

exercises/collatz-conjecture/package.json

@@ -0,0 +1,14 @@
+{
+    "description": "Exercism/Elm",
+    "repository": "https://github.com/exercism/elm.git",
+    "license": "MIT",
+    "scripts": {
+        "postinstall": "elm-package install -y",
+        "watch": "elm-test --watch",
+        "test": "elm-test"
+    },
+    "dependencies": {
+        "elm": "0.18.0",
+        "elm-test": "0.18.3"
+    }
+}

exercises/collatz-conjecture/tests/Tests.elm

@@ -0,0 +1,38 @@
+module Tests exposing (..)
+
+import Test exposing (..)
+import Expect
+import CollatzConjecture exposing (collatz)
+
+
+tests : Test
+tests =
+    describe "CollatzConjecture tests"
+        [ test "zero steps for one" <|
+            \() ->
+                Expect.equal (Ok 0) (collatz 1)
+
+        -- Once you get the first test passing, remove the
+        -- `skip <|` (just leave the comma) on the next
+        -- lines to continue!
+        , skip <|
+            test "divide if even" <|
+                \() ->
+                    Expect.equal (Ok 4) (collatz 16)
+        , skip <|
+            test "even and odd step" <|
+                \() ->
+                    Expect.equal (Ok 9) (collatz 12)
+        , skip <|
+            test "Large number of even and odd step" <|
+                \() ->
+                    Expect.equal (Ok 152) (collatz 1000000)
+        , skip <|
+            test "zero is an error" <|
+                \() ->
+                    Expect.equal (Err "Only positive numbers are allowed") (collatz 0)
+        , skip <|
+            test "negative values is an error" <|
+                \() ->
+                    Expect.equal (Err "Only positive numbers are allowed") (collatz -15)
+        ]

exercises/collatz-conjecture/tests/elm-package.json

@@ -0,0 +1,16 @@
+{
+    "version": "3.0.0",
+    "summary": "Exercism problems in Elm.",
+    "repository": "https://github.com/exercism/elm.git",
+    "license": "BSD3",
+    "source-directories": [
+        ".",
+        ".."
+    ],
+    "exposed-modules": [],
+    "dependencies": {
+        "elm-lang/core": "5.0.0 <= v < 6.0.0",
+        "elm-community/elm-test": "4.0.0 <= v < 5.0.0"
+    },
+    "elm-version": "0.18.0 <= v < 0.19.0"
+}