gcc/testsuite/go.test/test/bench/fannkuch.c

   1 /*
   2 Redistribution and use in source and binary forms, with or without
   3 modification, are permitted provided that the following conditions are met:
   4
   5     * Redistributions of source code must retain the above copyright
   6     notice, this list of conditions and the following disclaimer.
   7
   8     * Redistributions in binary form must reproduce the above copyright
   9     notice, this list of conditions and the following disclaimer in the
  10     documentation and/or other materials provided with the distribution.
  11
  12     * Neither the name of "The Computer Language Benchmarks Game" nor the
  13     name of "The Computer Language Shootout Benchmarks" nor the names of
  14     its contributors may be used to endorse or promote products derived
  15     from this software without specific prior written permission.
  16
  17 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  18 AND 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 COPYRIGHT OWNER OR CONTRIBUTORS BE
  21 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  22 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  23 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  24 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  25 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  26 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  27 POSSIBILITY OF SUCH DAMAGE.
  28 */
  29
  30 /*
  31  * The Computer Language Shootout
  32  * http://shootout.alioth.debian.org/
  33  * Contributed by Heiner Marxen
  34  *
  35  * "fannkuch"   for C gcc
  36  *
  37  * $Id: fannkuch.1.gcc.code,v 1.15 2009-04-28 15:39:31 igouy-guest Exp $
  38  */
  39
  40 #include <stdio.h>
  41 #include <stdlib.h>
  42
  43 #define Int     int
  44 #define Aint    int
  45
  46     static long
  47 fannkuch( int n )
  48 {
  49     Aint*       perm;
  50     Aint*       perm1;
  51     Aint*       count;
  52     long        flips;
  53     long        flipsMax;
  54     Int         r;
  55     Int         i;
  56     Int         k;
  57     Int         didpr;
  58     const Int   n1      = n - 1;
  59
  60     if( n < 1 ) return 0;
  61
  62     perm  = calloc(n, sizeof(*perm ));
  63     perm1 = calloc(n, sizeof(*perm1));
  64     count = calloc(n, sizeof(*count));
  65
  66     for( i=0 ; i<n ; ++i ) perm1[i] = i;        /* initial (trivial) permu */
  67
  68     r = n; didpr = 0; flipsMax = 0;
  69     for(;;) {
  70         if( didpr < 30 ) {
  71             for( i=0 ; i<n ; ++i ) printf("%d", (int)(1+perm1[i]));
  72             printf("\n");
  73             ++didpr;
  74         }
  75         for( ; r!=1 ; --r ) {
  76             count[r-1] = r;
  77         }
  78
  79 #define XCH(x,y)        { Aint t_mp; t_mp=(x); (x)=(y); (y)=t_mp; }
  80
  81         if( ! (perm1[0]==0 || perm1[n1]==n1) ) {
  82             flips = 0;
  83             for( i=1 ; i<n ; ++i ) {    /* perm = perm1 */
  84                 perm[i] = perm1[i];
  85             }
  86             k = perm1[0];               /* cache perm[0] in k */
  87             do {                        /* k!=0 ==> k>0 */
  88                 Int     j;
  89                 for( i=1, j=k-1 ; i<j ; ++i, --j ) {
  90                     XCH(perm[i], perm[j])
  91                 }
  92                 ++flips;
  93                 /*
  94                  * Now exchange k (caching perm[0]) and perm[k]... with care!
  95                  * XCH(k, perm[k]) does NOT work!
  96                  */
  97                 j=perm[k]; perm[k]=k ; k=j;
  98             }while( k );
  99             if( flipsMax < flips ) {
 100                 flipsMax = flips;
 101             }
 102         }
 103
 104         for(;;) {
 105             if( r == n ) {
 106                 return flipsMax;
 107             }
 108             /* rotate down perm[0..r] by one */
 109             {
 110                 Int     perm0 = perm1[0];
 111                 i = 0;
 112                 while( i < r ) {
 113                     k = i+1;
 114                     perm1[i] = perm1[k];
 115                     i = k;
 116                 }
 117                 perm1[r] = perm0;
 118             }
 119             if( (count[r] -= 1) > 0 ) {
 120                 break;
 121             }
 122             ++r;
 123         }
 124     }
 125 }
 126
 127     int
 128 main( int argc, char* argv[] )
 129 {
 130     int         n = (argc>1) ? atoi(argv[1]) : 0;
 131
 132     printf("Pfannkuchen(%d) = %ld\n", n, fannkuch(n));
 133     return 0;
 134 }