[ch-083/jeongoon] Haskell Solution added

3 files changed, 98 insertions, 0 deletions

diff --git a/challenge-083/jeongoon/haskell/Combinations.hs b/challenge-083/jeongoon/haskell/Combinations.hs
new file mode 100644
index 0000000000..f8c5324f43
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+++ b/challenge-083/jeongoon/haskell/Combinations.hs
@@ -0,0 +1,25 @@
+{- Copyright (c) 2020 JEON Myoungjin <jeongoon@g... > -}
+
+module Combinations
+  ( combinations
+  ) where
+
+combinations :: [a] -> Int -> [[a]]
+combinations []     _  = []
+combinations (m:ms) 1 = [m] : (combinations ms 1)
+combinations [_]    2 = []
+combinations [e,f]  2 = sequence [ [e],[f] ]
+combinations (m:ms) 2 = sequence [ [m],  ms ] ++ (combinations ms 2)
+combinations mls    n =
+  case totalLen `compare` n of
+    LT -> []
+    EQ -> [mls]
+    _  -> [ let leaders = map (mls!!) ids
+            in  leaders ++ followers |
+            ids <- combinations [ 0 .. room ] n',
+            let skipCount = (last ids) + 1,
+                followers <- (combinations (drop skipCount mls) 2) ]
+  where
+    totalLen    = length mls
+    room        = totalLen - 2
+    n'          = n - 2
diff --git a/challenge-083/jeongoon/haskell/ch-1.hs b/challenge-083/jeongoon/haskell/ch-1.hs
new file mode 100644
index 0000000000..1d108ae629
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+++ b/challenge-083/jeongoon/haskell/ch-1.hs
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+import System.Environment
+import System.Exit
+
+{- test with:
+runhaskell ch-1.hs "Perl W e e k l y Challenge" # output: 6
+-}
+main = do
+  args <- getArgs;
+  if length args /= 1
+    then die "Usage: runhaskell ch-1.hs <a string with 3 or more words"
+    else let ws = words (args !! 0)
+             wl = length ws
+         in
+           if wl < 3 then die "we need 3 words at least"
+           else (putStrLn.
+                 show.
+                 length.
+                 foldr1 (++).
+                 take (wl-2).
+                 drop 1) ws
diff --git a/challenge-083/jeongoon/haskell/ch-2.hs b/challenge-083/jeongoon/haskell/ch-2.hs
new file mode 100644
index 0000000000..c64170400a
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+++ b/challenge-083/jeongoon/haskell/ch-2.hs
@@ -0,0 +1,53 @@
+import System.Environment
+import System.Exit
+import Data.Char (isNumber)
+import Data.Maybe (isJust, catMaybes)
+import Data.List (sum)
+import Combinations (combinations)
+
+
+{- test with:
+   runhaskell ch-2.hs 12 7 4 # answer: 12
+   runhaskell ch-2.hs 12 7 4 5 6 9 20 12 7 4 5 6 9 20 9 4 2 1 13 8 # answer: 6
+ # or in order to get faster result, you can compile and execute:
+   ghc ch-2.hs
+   ./ch-2 12 7 4 5 6 9 20 12 7 4 5 6 9 20 9 4 2 1 13 8 # answer: 6
+-}
+
+answerFlipArray :: (Integral a) => [a] -> Int
+answerFlipArray nums
+  | totalSum == 1 = 0
+  | otherwise = answerWith totalSum totalLen numCombis
+  where
+    totalSum  = sum nums
+    totalLen  = length nums
+    halfLen   = totalLen `div` 2
+    numCombis = (foldr1 (++) .
+                    map (combinations nums))
+                   [ 1 .. halfLen ]
+
+    answerWith _      minElems [] = minElems
+    answerWith minSum minElems (aCombi:otherCombis) =
+      case (positiveSum `compare` minSum) of
+        LT -> answerWith positiveSum newElems otherCombis
+        EQ -> answerWith minSum (min newElems minElems) otherCombis
+        GT -> answerWith minSum minElems otherCombis
+      where
+        len  = length aCombi
+        sm   = sum aCombi
+        sm'  = totalSum - sm
+        (positiveSum, newElems) =
+            case (sm `compare` sm') of
+              LT -> ( sm' - sm, len )
+              EQ -> (        0, (min len (totalLen - len)) )
+              GT -> ( sm - sm', (totalLen - len) )
+
+main = do
+    (catMaybes.map (\nStr ->
+                       if (all isNumber nStr) then Just(read nStr :: Int)
+                       else Nothing )) `fmap` getArgs
+      >>= (\nums ->
+              if length nums < 1 then
+                die "Usage: runhaskell ch-2.hs <natural num> ..."
+              else
+                putStrLn $ show ( answerFlipArray nums ) )