Haskell Solution to Google Code Jam 2019 Qualifying Round Problem 2.

ycgyow.hs

import Control.Monad

sampleMoves = "EESSSESE"

applyMove :: (Int, Int) -> Char -> (Int, Int)
applyMove (row, col) move
    | move == 'S' = (row+1, col)
    | move == 'E' = (row, col+1)
    | otherwise = (row, col)

flipMove :: Char -> Char
flipMove c
    | c == 'S' = 'E'
    | c == 'E' = 'S'
    | otherwise = c

getTrajectory :: String -> [(Int, Int)]
getTrajectory moves = scanl applyMove (1, 1) moves

solveCase :: (Int, Int, String) -> (Int, String)
solveCase (i, n, lydiasMoves)
    | n == 2 = (i, reverse lydiasMoves)
    | otherwise = (i, map flipMove lydiasMoves)

caseOutput :: (Int, String) -> IO ()
caseOutput (i, str) = putStrLn ("Case #" ++ show i ++ ": " ++ str)

readCase :: Int -> IO (Int, Int, String)
readCase i = do
    nstr <- getLine
    let n = (read nstr) :: Int
    moves <- getLine
    return (i, n, filter (\c -> (c /= '\r') && (c /= '\n')) moves)

main = do
    t <- getLine
    let tn = (read t) :: Int
    cases <- forM [1..tn] readCase
    let solutions = map solveCase cases
    mapM_ caseOutput solutions