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Diffstat (limited to 'challenge-083/jeongoon/haskell/ch-2.hs')
| -rw-r--r-- | challenge-083/jeongoon/haskell/ch-2.hs | 53 |
1 files changed, 53 insertions, 0 deletions
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 --- /dev/null +++ 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 ) ) |