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<?php $arrayMax = function ($max, $value) use (&$arrayMax) { if (is_array($value)) return array_reduce($value, $arrayMax, $max); elseif (is_int($value)) return $max === null ? $value : max($max, $value); else return $max; }; var_dump(array_reduce([5, 7, 2, ['25', [20]]], $arrayMax));

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38.22 ms | 402 KiB | 5 Q