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      1 {-
      2 /*	$NetBSD: lru.hs,v 1.1 2006/10/09 12:32:46 yamt Exp $	*/
      3 
      4 /*-
      5  * Copyright (c)2005 YAMAMOTO Takashi,
      6  * All rights reserved.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     27  * SUCH DAMAGE.
     28  */
     29 -}
     30 
     31 import System.Environment
     32 import System.IO
     33 import List
     34 import Maybe
     35 
     36 contain x xs = isJust $ find (== x) xs
     37 
     38 do_lru1 npg n q qlen [] = (reverse n, q)
     39 do_lru1 npg n q qlen rs@(r:rs2) =
     40 	if contain r q then
     41 		let
     42 			nq = delete r q
     43 		in
     44 		do_lru1 npg n (r:nq) qlen rs2
     45 	else if qlen < npg then
     46 		do_lru1 npg (r:n) (r:q) (qlen+1) rs2
     47 	else
     48 		let
     49 			nq = take (qlen-1) q
     50 		in
     51 		do_lru1 npg (r:n) (r:nq) qlen rs2
     52 
     53 do_lru npg rs = fst $ do_lru1 npg [] [] 0 rs
     54 
     55 main = do
     56 	xs <- getContents
     57 	args <- getArgs
     58 	let
     59 		ls = lines xs
     60 		npgs::Int
     61 		npgs = read $ args !! 0
     62 		pgs::[Int]
     63 		pgs = map read ls
     64 	mapM_ print $ do_lru npgs pgs
     65