542f4ab0a0
* Adding binary search example for Haskell * Adding selection sort example in Haskell * Adding Haskell examples for chapter 3 * Adding examples for chapter 4 * Adding examples for chapter 5 * Adding git ignore * Add Haskell example for BFS * resetting * Adding haskell example for dijkstras algorithm * Adding Haskell example for chapter 8 * Adding power set based solution for set covering problem * Adding Haskell examples for chap 9
28 lines
795 B
Haskell
28 lines
795 B
Haskell
import Control.Applicative
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import Data.List
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import qualified Data.Set as Set
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import qualified Data.HashMap.Strict as Map
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items = Map.fromList [
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("stereo", (4, 3000)),
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("laptop", (3, 2000)),
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("guitar", (1, 1500))
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]
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value set = (a, b)
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where
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weightandvalues = (sequence $ map (`Map.lookup` items) set)
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Just (a,b) = Just (foldl (\(a,b) (c,d) -> (a+c, b+d)) (0,0)) <*> weightandvalues
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powerSet xs = foldl (\acc x -> acc ++ (map (\e -> x:e) acc)) [[]] xs
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solution = foldl
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(\acc v -> let
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(firstweight, firstvalue) = value acc
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(secondweight, secondvalue) = value v
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in if firstweight <= 4 && firstvalue >= secondvalue then acc else if secondweight <= 4 then v else acc)
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first
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rest
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where
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(first: rest) = filter (not . null) $ powerSet $ (Map.keys items)
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