module Main where import System.Environment import System.Exit (exitWith, ExitCode(ExitFailure)) import Data.List (intercalate) -- Recursively find longest common subsequence lcs :: Eq a => [a] -> [a] -> [a] lcs  bs =  lcs as  =  lcs (a:as) (b:bs) | a == b = (lcs as bs) ++ [a] | otherwise = longest (lcs (a:as) bs) (lcs as (b:bs)) -- Returns the longer of two lists longest :: Foldable t => t a -> t a -> t a longest l1 l2 | length l1 > length l2 = l1 | otherwise = l2 -- Converts string in format "1, 2, 3" to a list of integers stringToList :: String -> [Int] stringToList str = read $ "[" ++ str ++ "]" :: [Int] listToString :: [Int] -> String listToString = intercalate ", " . map show main :: IO () main = do args <- getArgs let l1 = stringToList $ head args :: [Int] let l2 = stringToList $ head $ tail args :: [Int] if length args /= 2 then do putStrLn "Usage: please provide two lists in the format \"1, 2, 3, 4, 5\"" exitWith $ ExitFailure 1 else putStrLn $ listToString $ reverse $ lcs l1 l2
Longest Common Subsequence in Haskell was written by:
If you see anything you'd like to change or update, please consider contributing.
No 'How to Implement the Solution' section available. Please consider contributing.
No 'How to Run the Solution' section available. Please consider contributing.