app/cses1754.hs

   1 import Control.Monad
   2
   3 main :: IO ()
   4 main = do
   5   line1 <- getLine
   6   let numQuestions = read line1 :: Int
   7   answers <- forM [1..numQuestions] $ \_ -> do
   8     q <- getQuestion
   9     return $ solve q
  10   putStrLn $ unlines $ map showA answers
  11
  12 getQuestion :: IO (Int, Int)
  13 getQuestion = do
  14   line <- getLine
  15   let question = map read $ words line
  16   return (question !! 0, question !! 1)
  17
  18
  19 solve :: (Int, Int) -> Bool
  20 solve (0, 0) = True
  21 solve (0, _) = False
  22 solve (_, 0) = False
  23 solve (nLeft, nRight) = (a <= b * 2) && ((b - n) `mod` 3 == 0)
  24   where a = max nLeft nRight
  25         b = min nLeft nRight
  26         n = a - b
  27
  28 showA :: Bool -> String
  29 showA True = "YES"
  30 showA False = "NO"