September 2017 Update

Task/Knapsack-problem-Continuous/Haskell/knapsack-problem-continuous-1.hs

@@ -1,40 +1,49 @@
-import Control.Monad
 import Data.List (sortBy)
 import Data.Ord (comparing)
+import Text.Printf (printf)
+import Control.Monad (forM_)
 import Data.Ratio (numerator, denominator)
-import Text.Printf
 
+maxWgt :: Rational
 maxWgt = 15
 
 data Bounty = Bounty
-   {itemName :: String,
-    itemVal, itemWgt :: Rational}
+  { itemName :: String
+  , itemVal, itemWgt :: Rational
+  }
 
+items :: [Bounty]
 items =
-   [Bounty  "beef"     36  3.8,
-    Bounty  "pork"     43  5.4,
-    Bounty  "ham"      90  3.6,
-    Bounty  "greaves"  45  2.4,
-    Bounty  "flitch"   30  4.0,
-    Bounty  "brawn"    56  2.5,
-    Bounty  "welt"     67  3.7,
-    Bounty  "salami"   95  3.0,
-    Bounty  "sausage"  98  5.9]
+  [ Bounty "beef" 36 3.8
+  , Bounty "pork" 43 5.4
+  , Bounty "ham" 90 3.6
+  , Bounty "greaves" 45 2.4
+  , Bounty "flitch" 30 4.0
+  , Bounty "brawn" 56 2.5
+  , Bounty "welt" 67 3.7
+  , Bounty "salami" 95 3.0
+  , Bounty "sausage" 98 5.9
+  ]
 
 solution :: [(Rational, Bounty)]
 solution = g maxWgt $ sortBy (flip $ comparing f) items
-  where g room (b@(Bounty _ _ w) : bs) = if w < room
-          then (w, b) : g (room - w) bs
-          else [(room, b)]
-        f (Bounty _ v w) = v / w
+  where
+    g room (b@(Bounty _ _ w):bs) =
+      if w < room
+        then (w, b) : g (room - w) bs
+        else [(room, b)]
+    f (Bounty _ v w) = v / w
 
+main :: IO ()
 main = do
-    forM_ solution $ \(w, b) ->
-        printf "%s kg of %s\n" (mixedNum w) (itemName b)
-    printf "Total value: %s\n" $ mixedNum $ sum $ map f solution
-  where f (w, Bounty _ v wtot) = v * (w / wtot)
-        mixedNum q = if b == 0
-            then show a
-            else printf "%d %d/%d" a (numerator b) (denominator b)
-          where a = floor q
-                b = q - toEnum a
+  forM_ solution $ \(w, b) -> printf "%s kg of %s\n" (mixedNum w) (itemName b)
+  (printf "Total value: %s\n" . mixedNum . sum) $ f <$> solution
+  where
+    f (w, Bounty _ v wtot) = v * (w / wtot)
+    mixedNum q =
+      if b == 0
+        then show a
+        else printf "%d %d/%d" a (numerator b) (denominator b)
+      where
+        a = floor q
+        b = q - toEnum a

Task/Knapsack-problem-Continuous/Haskell/knapsack-problem-continuous-2.hs

@@ -3,21 +3,24 @@ import Data.Ord (comparing)
 import Text.Printf (printf)
 
 -- (name, (value, weight))
-items = [("beef",    (36, 3.8)),
-         ("pork",    (43, 5.4)),
-         ("ham",     (90, 3.6)),
-         ("greaves", (45, 2.4)),
-         ("flitch",  (30, 4.0)),
-         ("brawn",   (56, 2.5)),
-         ("welt",    (67, 3.7)),
-         ("salami",  (95, 3.0)),
-         ("sausage", (98, 5.9))]
+items =
+  [ ("beef", (36, 3.8))
+  , ("pork", (43, 5.4))
+  , ("ham", (90, 3.6))
+  , ("greaves", (45, 2.4))
+  , ("flitch", (30, 4.0))
+  , ("brawn", (56, 2.5))
+  , ("welt", (67, 3.7))
+  , ("salami", (95, 3.0))
+  , ("sausage", (98, 5.9))
+  ]
 
-unitWeight (_, (val, weight)) = (fromIntegral val) / weight
+unitWeight (_, (val, weight)) = fromIntegral val / weight
 
 solution k = loop k . sortBy (flip $ comparing unitWeight)
-    where loop k ((name, (_, weight)):xs)
-              | weight < k = putStrLn ("Take all the " ++ name) >> loop (k-weight) xs
-              | otherwise  = printf "Take %.2f kg of the %s\n" (k :: Float) name
+  where
+    loop k ((name, (_, weight)):xs)
+      | weight < k = putStrLn ("Take all the " ++ name) >> loop (k - weight) xs
+      | otherwise = printf "Take %.2f kg of the %s\n" (k :: Float) name
 
 main = solution 15 items