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135 lines
3.4 KiB
C
135 lines
3.4 KiB
C
/*
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* Neither the name of "The Computer Language Benchmarks Game" nor the
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name of "The Computer Language Shootout Benchmarks" nor the names of
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its contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* The Computer Language Shootout
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* http://shootout.alioth.debian.org/
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* Contributed by Heiner Marxen
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*
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* "fannkuch" for C gcc
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*
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* $Id: fannkuch.1.gcc.code,v 1.15 2009-04-28 15:39:31 igouy-guest Exp $
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#define Int int
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#define Aint int
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static long
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fannkuch( int n )
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{
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Aint* perm;
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Aint* perm1;
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Aint* count;
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long flips;
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long flipsMax;
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Int r;
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Int i;
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Int k;
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Int didpr;
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const Int n1 = n - 1;
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if( n < 1 ) return 0;
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perm = calloc(n, sizeof(*perm ));
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perm1 = calloc(n, sizeof(*perm1));
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count = calloc(n, sizeof(*count));
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for( i=0 ; i<n ; ++i ) perm1[i] = i; /* initial (trivial) permu */
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r = n; didpr = 0; flipsMax = 0;
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for(;;) {
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if( didpr < 30 ) {
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for( i=0 ; i<n ; ++i ) printf("%d", (int)(1+perm1[i]));
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printf("\n");
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++didpr;
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}
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for( ; r!=1 ; --r ) {
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count[r-1] = r;
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}
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#define XCH(x,y) { Aint t_mp; t_mp=(x); (x)=(y); (y)=t_mp; }
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if( ! (perm1[0]==0 || perm1[n1]==n1) ) {
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flips = 0;
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for( i=1 ; i<n ; ++i ) { /* perm = perm1 */
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perm[i] = perm1[i];
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}
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k = perm1[0]; /* cache perm[0] in k */
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do { /* k!=0 ==> k>0 */
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Int j;
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for( i=1, j=k-1 ; i<j ; ++i, --j ) {
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XCH(perm[i], perm[j])
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}
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++flips;
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/*
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* Now exchange k (caching perm[0]) and perm[k]... with care!
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* XCH(k, perm[k]) does NOT work!
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*/
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j=perm[k]; perm[k]=k ; k=j;
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}while( k );
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if( flipsMax < flips ) {
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flipsMax = flips;
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}
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}
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for(;;) {
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if( r == n ) {
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return flipsMax;
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}
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/* rotate down perm[0..r] by one */
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{
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Int perm0 = perm1[0];
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i = 0;
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while( i < r ) {
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k = i+1;
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perm1[i] = perm1[k];
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i = k;
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}
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perm1[r] = perm0;
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}
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if( (count[r] -= 1) > 0 ) {
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break;
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}
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++r;
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}
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}
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}
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int
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main( int argc, char* argv[] )
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{
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int n = (argc>1) ? atoi(argv[1]) : 0;
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printf("Pfannkuchen(%d) = %ld\n", n, fannkuch(n));
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return 0;
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}
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