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<?php function isQuadtree($bits, &$i){ $i++; if ($i >= strlen($bits)) return false; if ($bits[$i] === "1") { isQuadtree($bits, $i); isQuadtree($bits, $i); isQuadtree($bits, $i); return isQuadtree($bits, $i); } return true; } $k = -1; var_dump(isQuadtree("110000", $k));
Output for 8.1.34, 8.2.27 - 8.2.30, 8.3.0 - 8.3.29, 8.4.1 - 8.4.16, 8.5.0 - 8.5.1
bool(false)

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