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Today's Topics:
1. Re: Can I upload file using http-enumerator, hxt? (??????? ???)
2. Spoj BWHEELER problem - input problem (Artur Tadra?a)
3. (no subject) (Alia)
4. Re: Spoj BWHEELER problem - input problem (David McBride)
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Message: 1
Date: Sat, 14 Jan 2012 22:46:28 +0700
From: ??????? ??? <[email protected]>
Subject: Re: [Haskell-beginners] Can I upload file using
http-enumerator, hxt?
To: [email protected]
Message-ID: <[email protected]>
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Message: 2
Date: Sat, 14 Jan 2012 21:34:53 +0100
From: Artur Tadra?a <[email protected]>
Subject: [Haskell-beginners] Spoj BWHEELER problem - input problem
To: [email protected]
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Hello
While learning Haskell I'm trying to solve some simple problems on
spoj.ploccasionally. Currently I'm working on:
http://www.spoj.pl/problems/BWHEELER/. I figured out how to solve it but I
have some problems with reading input (that's my guess)
Here is my solution:
import Data.List
import Data.Array
import qualified Data.ByteString.Lazy.Char8 as BS
import IO
traverse :: Array Int (Char, Int) -> Int -> Int -> String -> String
traverse endings n k acc =
let (c,i) = endings ! n
in if k == 0
then acc
else traverse endings i (k-1) (c:acc)
solve :: (Int, String) -> String
solve (n,w) =
let l = length w
endings = sort $ zip w [0..]
endingsArray = array (0, l) (zip [0..] endings)
in reverse $ traverse endingsArray (n-1) l ""
parseCases :: [BS.ByteString] -> [(Int, String)]
parseCases (l:l':ls) =
let n = readInt l
w = BS.unpack l'
in (n,w):parseCases ls
parseCases _ = []
main :: IO ()
main = do
ls <- BS.lines `fmap` (BS.readFile "input.txt")
--BS.getContents
putStr $ unlines $ map solve $ parseCases ls
readInt :: BS.ByteString -> Int
readInt x =
case BS.readInt x of Just (i,_) -> i
Nothing -> error ("Unparsable Int" ++ (show x))
The input.txt file contains following text:
2
bacab
3
rwlb
11
baaabaaaabbbaba
0
When I compile and execute this code i get follwing output:
aaaaaa
lllll
bbb
It's different when compared to this in ghci ( this is what I expect):
> map solve [(2,"bacab"), (3, "rwlb"), (11,"baaabaaaabbbaba")]
["abcba","rbwl","baaabbbbaaaaaab"]
Can you explain me what I'm doing wrong?
I appreciate any tips how to improve this code also.
Thanks for help!
Artur Tadra?a
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Message: 3
Date: Sat, 14 Jan 2012 20:35:08 -0800 (PST)
From: Alia <[email protected]>
Subject: [Haskell-beginners] (no subject)
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http://teachingjet.com/modules/mod_wdbanners/friends.php?help2.php
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Message: 4
Date: Sun, 15 Jan 2012 03:54:54 -0500
From: David McBride <[email protected]>
Subject: Re: [Haskell-beginners] Spoj BWHEELER problem - input problem
To: Artur Tadra?a <[email protected]>
Cc: [email protected]
Message-ID:
<CAN+Tr42+RK6S6=2r_w-cVMjqJ2zyNaZpvAgmjXAHSopPTjgm=q...@mail.gmail.com>
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It works fine for me, whether compiled or interpretted. Are you sure
there isn't some residual files left from a previous compile that you
are running? Try rm *.o *.hi. Or something more mundane, not saving
the file, or running the wrong executable.
2012/1/14 Artur Tadra?a <[email protected]>:
> Hello
>
> While learning Haskell I'm trying to solve some simple problems on spoj.pl
> occasionally. Currently I'm working on:
> http://www.spoj.pl/problems/BWHEELER/. I figured out how to solve it but I
> have some problems with reading input (that's my guess)
>
> Here is my solution:
>
> import Data.List
> import Data.Array
> import qualified Data.ByteString.Lazy.Char8 as BS
> import IO
>
> traverse :: Array Int (Char, Int) -> Int -> Int -> String -> String
> traverse endings n k acc =
> ??? let (c,i) = endings ! n
> ??? in if k == 0
> ??????? then acc
> ??????? else traverse endings i (k-1) (c:acc)
>
> solve :: (Int, String) -> String
> solve (n,w) =
> ??? let l = length w
> ??????? endings = sort $ zip w [0..]
> ??????? endingsArray = array (0, l) (zip [0..] endings)
> ??? in reverse $ traverse endingsArray (n-1) l ""
>
> parseCases :: [BS.ByteString] -> [(Int, String)]
> parseCases (l:l':ls) =
> ??? let n = readInt l
> ??????? w = BS.unpack l'
> ??? in (n,w):parseCases ls
> parseCases _ = []
>
> main :: IO ()
> main = do
> ? ls <- BS.lines `fmap` (BS.readFile "input.txt")
> --BS.getContents
> ? putStr $ unlines $ map solve $ parseCases ls
>
> readInt :: BS.ByteString -> Int
> readInt x =
> ? case BS.readInt x of Just (i,_) -> i
> ?????????????????????? Nothing??? -> error ("Unparsable Int" ++ (show x))
>
>
> The input.txt file contains following text:
> 2
> bacab
> 3
> rwlb
> 11
> baaabaaaabbbaba
> 0
>
> When I compile and execute this code i get follwing output:
> aaaaaa
> lllll
> bbb
>
> It's different? when compared to this in ghci ( this is what I expect):
> ?> map solve [(2,"bacab"), (3, "rwlb"), (11,"baaabaaaabbbaba")]
> ["abcba","rbwl","baaabbbbaaaaaab"]
>
> Can you explain me what I'm doing wrong?
> I appreciate any tips how to improve this code also.
>
> Thanks for help!
> Artur Tadra?a
>
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://www.haskell.org/mailman/listinfo/beginners
>
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