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module Main where
import Data.Int
import Data.Array.Base
import Data.Array.ST
import Control.Monad.ST
import System.Environment
main :: IO ()
main = do
[_nr, _len] <- getArgs
let nRounds = read _nr :: Int
len = read _len :: Int
stToIO $ do
arr <- newArray (1, len) 0
let spin :: STUArray s Int Int -> Int -> Int -> Int -> ST s ()
spin _ r i n | i > n = return ()
spin arr r i n = do x <- unsafeRead arr i
unsafeWrite arr i $ x + r
spin arr r (i + 1) n
loop :: STUArray s Int Int -> Int -> ST s ()
loop _ r | r > nRounds = return ()
loop arr r = do
k <- getNumElements arr
spin arr r 0 (k - 1)
loop arr (r + 1)
loop arr 1
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