Submission #51341998

---

Source Code Expand

{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE BlockArguments #-}
{-# LANGUAGE FlexibleContexts #-}
{-# HLINT ignore "Use lambda-case" #-}
{-# LANGUAGE TupleSections #-}
{-# LANGUAGE TypeApplications #-}
{-# OPTIONS_GHC -Wno-unrecognised-pragmas #-}

module Main where

import qualified Data.List as L

main :: IO ()
main = do
  s <- getLine

  let n = toInteger $ length s
  let r = length (L.nub s)

  print $ if r == 1 then 1 else choose n 2 - sum [choose (toInteger (length xs)) 2 | xs <- L.group $ L.sort s, length xs >= 2]

fact :: Integer -> Integer
fact n
  | n == 0 = 1
  | n > 0 = n * fact (n - 1)
  | otherwise = error "invalid number"

choose :: Integer -> Integer -> Integer
choose n r
  | r < 0 || r > n = error "invalid arguments"
  | otherwise = fact n `div` (fact r * fact (n - r))

Submission Info

Judge Result