1.php

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

   contributed by Peter Baltruschat
   modified by Levi Cameron
   *reset*
*/

class Node
{
    public $l;
    public $r;
}

function bottomUpTree($depth)
{
    $node = new Node();
    if (!$depth) return $node;
    $depth--;
    $node->l = bottomUpTree($depth);
    $node->r = bottomUpTree($depth);
    return $node;
}

function itemCheck($treeNode)
{
    return 1
        + ($treeNode->l->l === null ? 1 : itemCheck($treeNode->l))
        + ($treeNode->r->l === null ? 1 : itemCheck($treeNode->r));
}

$minDepth = 4;

$n = ($argc == 2) ? $argv[1] : 1;
$maxDepth = max($minDepth + 2, $n);
$stretchDepth = $maxDepth + 1;

$stretchTree = bottomUpTree($stretchDepth);
printf("stretch tree of depth %d\t check: %d\n", $stretchDepth, itemCheck($stretchTree));
unset($stretchTree);

$longLivedTree = bottomUpTree($maxDepth);

$iterations = 1 << ($maxDepth);
do {
    $check = 0;
    for ($i = 1; $i <= $iterations; ++$i) {
        $t = bottomUpTree($minDepth);
        $check += itemCheck($t);
        unset($t);
    }

    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",
    $maxDepth,
    itemCheck($longLivedTree)
);