Make roughness independent of tile value

tfausak · Apr 6, 2014 · 222df4d · 222df4d
1 parent 5370a11
commit 222df4d
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Showing 2 changed files with 4 additions and 4 deletions.
diff --git a/library/Hs2048/AI.hs b/library/Hs2048/AI.hs
@@ -72,14 +72,14 @@ quality b = sum
     each other. Smooth boards are generally better.
 
     >>> roughness [[Just 2, Just 4]]
-    2
+    1
     >>> roughness [[Just 2, Just 2]]
     0
 
     Blank tiles are ignored for the purposes of calculating roughness.
 
     >>> roughness [[Just 2, Nothing, Just 4]]
-    2
+    1
 -}
 roughness :: B.Board -> Int
 roughness b = boardRoughness b + boardRoughness (B.rotate b)
@@ -96,6 +96,6 @@ duplicates :: B.Board -> [[Int]]
 duplicates = group . sort . (=<<) catMaybes
 
 vectorRoughness :: V.Vector -> Int
-vectorRoughness v = sum (fmap abs (zipWith subtract ts (tail ts)))
+vectorRoughness v = length (filter id (zipWith (/=) ts (tail ts)))
   where
     ts = catMaybes v
diff --git a/test-suite/Hs2048/AISpec.hs b/test-suite/Hs2048/AISpec.hs
@@ -34,4 +34,4 @@ spec = do
             roughness [] `shouldBe` 0
 
         it "calculates the roughness of a board" $ do
-            roughness b `shouldBe` 5734
+            roughness b `shouldBe` 16