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author | Joe Zhao <ztuowen@gmail.com> | 2015-03-31 23:41:55 +0800 |
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committer | Joe Zhao <ztuowen@gmail.com> | 2015-03-31 23:41:55 +0800 |
commit | a9abc1da41b56edbed00081800382e854d6698d0 (patch) | |
tree | 5265cc1c5296768438b67299afd59bcc57c58f0c /H23.hs | |
parent | 378f6303e8860b7bbca7dea787d584a6728cebf1 (diff) | |
download | h99-a9abc1da41b56edbed00081800382e854d6698d0.tar.gz h99-a9abc1da41b56edbed00081800382e854d6698d0.tar.bz2 h99-a9abc1da41b56edbed00081800382e854d6698d0.zip |
rename to H**, +31 +32 +33 +34 +35 +36
Diffstat (limited to 'H23.hs')
-rw-r--r-- | H23.hs | 21 |
1 files changed, 21 insertions, 0 deletions
@@ -0,0 +1,21 @@ +import System.Random +import Data.List + +rnd_select :: [a] -> Int -> IO [a] +rnd_select _ 0 = return [] +rnd_select (x:xs) n = + do + r <- randomRIO (0, (length xs)) + if r < n + then do + rest <- rnd_select xs (n-1) + return (x : rest) + else rnd_select xs n + +rnd_select' xs n = do + gen <- getStdGen + return $ take n [ xs !! x | x <- randomRs (0, (length xs) - 1) gen] + +rnd_select'' :: Int -> [a] -> [a] +rnd_select'' n x = map (x!!) is + where is = take n . nub $ randomRs (0, length x - 1) (mkStdGen 100) |