The Computer Language
Benchmarks Game

binary-trees Hack #2 program

<?hh
/* The Computer Language Benchmarks Game
   http://benchmarksgame.alioth.debian.org/

   contributed by Peter Baltruschat
   modified by Levi Cameron
   modified by Craig Russell
   PHP as HHVM/Hack by Isaac Gouy
   *reset*
*/

class Tree {
   public $l;
   public $r;
   
   public function __construct($depth) {
      if($depth) {
         $this->l = new Tree(--$depth);
         $this->r = new Tree($depth);
      }
   }
   
   public function check() {
      return 1
         + ($this->l->l === null ? 1 : $this->l->check())
         + ($this->r->l === null ? 1 : $this->r->check());
   }
}

$minDepth = 4;

$n = $argc == 2 ? $argv[1] : 1;
$maxDepth = $minDepth + 2 > $n ? $minDepth + 2 : $n;
$stretchDepth = $maxDepth + 1;

$stretch = new Tree($stretchDepth);
printf("stretch tree of depth %d\t check: %d\n",
   $stretchDepth, $stretch->check());
unset($stretch);

$longLivedTree = new Tree($maxDepth);

$iterations = 1 << $maxDepth;
do
{
   $check = 0; 
   for($i = 1; $i <= $iterations; ++$i)
   {
      $check += (new Tree($minDepth))->check();
   }
   
   printf("%d\t trees of depth %d\t check: %d\n",
      $iterations, $minDepth, $check);
   
   $minDepth += 2;
   $iterations >>= 2;
}
while($minDepth <= $maxDepth);

printf("long lived tree of depth %d\t check: %d\n",
   $maxDepth, $longLivedTree->check());
    

NOTES:
64-bit Ubuntu quad core
HipHop VM 3.21.0 (rel)
Compiler: 3.21.0+dfsg-2
Repo schema: 1c159cf2047dca5f4a3363b2138a33e14a1e99fa


Wed, 15 Nov 2017 22:10:02 GMT

MAKE:
/usr/bin/hh_client
No errors!

0.06s to complete and log all make actions

COMMAND LINE:
/usr/bin/hhvm  -d hhvm.hack.lang.look_for_typechecker=0 binarytrees.hack-2.hack 21

PROGRAM OUTPUT:
stretch tree of depth 22	 check: 8388607
2097152	 trees of depth 4	 check: 65011712
524288	 trees of depth 6	 check: 66584576
131072	 trees of depth 8	 check: 66977792
32768	 trees of depth 10	 check: 67076096
8192	 trees of depth 12	 check: 67100672
2048	 trees of depth 14	 check: 67106816
512	 trees of depth 16	 check: 67108352
128	 trees of depth 18	 check: 67108736
32	 trees of depth 20	 check: 67108832
long lived tree of depth 21	 check: 4194303