fannkuch-redux PHP #8 program

<? /* The Computer Language Benchmarks Game
   https://salsa.debian.org/benchmarksgame-team/benchmarksgame/

   Naive transliteration from Rex Kerr's Scala program
   contributed by Isaac Gouy 
*/

function fannkuch($n) {
   $perm1 = new SplFixedArray($n);   
   for ($i = 0; $i < $n; $i++) $perm1[$i] = $i;      
   $perm = new SplFixedArray($n);
   $count = new SplFixedArray($n);       
   $f = $flips = $nperm = $checksum = $i = $k = $r = 0;           
  
   $r = $n;
   while ($r > 0) { 
      $i = 0;  
      while ($r != 1) { $count[$r-1] = $r; $r -= 1; }   
      while ($i < $n) { $perm[$i] = $perm1[$i]; $i += 1; }     
        
      // Count flips and update max and checksum
      $f = 0;
      $k = $perm[0];  
      while ($k != 0) {
         $i = 0;  
         while (2*$i < $k) {          
            $t = $perm[$i]; $perm[$i] = $perm[$k-$i]; $perm[$k-$i] = $t;  
            $i += 1;           
         }
         $k = $perm[0];
         $f += 1;   
      }         
      if ($f > $flips) $flips = $f;         
      if (($nperm & 0x1) == 0) $checksum += $f; else $checksum -= $f;
   
      // Use incremental change to generate another permutation   
      $more = true;
      while ($more) {   
         if ($r == $n) {
            echo $checksum, "\n";            
            return $flips; 
         }
         $p0 = $perm1[0];
         $i = 0;
         while ($i < $r) {
            $j = $i + 1;
            $perm1[$i] = $perm1[$j];
            $i = $j;            
         }
         $perm1[$r] = $p0; 
         
         $count[$r] -= 1;        
         if ($count[$r] > 0) $more = false; else $r += 1; 
      }
      $nperm += 1;
   }
   return $flips;      
}
   
$n = $argc > 1 ? $argv[1] : 7;       
printf("Pfannkuchen(%d) = %d\n", $n, fannkuch($n));

?>
    

NOTES:
64-bit Ubuntu quad core
PHP 8.4.1 (cli)
(built: Nov 22 2024 14:22:47) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.4.1,
with Zend OPcache v8.4.1,
Copyright (c) Zend Technologies


 Sat, 23 Nov 2024 03:54:42 GMT

COMMAND LINE:
 /opt/src/php-8.4.1/bin/php -dzend_extension=/opt/src/php-8.4.1/lib/php/extensions/no-debug-non-zts-20240924/opcache.so -dopcache.enable_cli=1 -dopcache.jit_buffer_size=64M -n  fannkuchredux.php-8.php 12

PROGRAM OUTPUT:
3968050
Pfannkuchen(12) = 65