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  1. Prepare
  2. Functional Programming
  3. Introduction
  4. Functions or Not?
  5. Discussions

Functions or Not?

  • Fiorix
     + 2 comments

    use this as pattern for IO:

    main :: IO ()
main = do
    n_temp <- getLine
    let n = read n_temp :: Int
    forM_ [1..n] $ \boh  -> do
        q_temp <- getLine
        let q = read q_temp :: Int
        rawInput <- getMultipleLines q
        let input = [(read (words str !! 0) :: Int, read (words str !! 1) :: Int ) | str <- rawInput]
        -- here starts your code


getMultipleLines :: Int -> IO [String]
getMultipleLines n
    | n <= 0 = return []
    | otherwise = do          
        x <- getLine         
        xs <- getMultipleLines (n-1)    
        let ret = (x:xs)    
        return ret

    It works with most input format of HackerRank:

    • First read and parse an integer (n_temp and n)
    • For n times read another number from input called q and read the next q lines with getMultipleLines. It returns a list of q lines as strings.
    • To parse the numbers inside a single line, use list comprehension to iterate on the lines and the function "words" to split the values. This code works if every line contains exactly two integers and put them in a list of type [(Int, Int)]