Question

If an array initialized as:

   $arr = array(array(141,151,161),2,3,array(101,102,array(303,404,606,555,789,array(1000,22,9999,array(9057,100000),522))));

Then the result should be: 100000

I have written a function to solve this problem but I need less bytes and less memory of codes.

My Function is:

function MaxArray($arr){
$length = count($arr);
global $maxValue;
for($i=0;$i<$length;$i++){
        if(is_int($arr[$i])){

                if($maxValue < $arr[$i]){
                    $maxValue = $arr[$i];
                }

        }
        elseif(is_array($arr[$i])){     
                MaxArray($arr[$i]);
            }
        }
    return $maxValue;   
}

Answer 1

Taken from PHP manual but authored by me:

/**
 * @param array $array
 *
 * @return int|null Returns the largest value of the array. Returns NULL if no 
 *     integers are found.
 */
function array_max_recursive(array $array) {
    $max = NULL;
    $stack = array($array);

    do {
        $current = array_pop($stack );
        foreach ($current as $value) {
            if (is_array($value)) {
                $stack[] = $value;
            } elseif (filter_var($value, FILTER_VALIDATE_INT) !== FALSE) {
                // max(NULL, 0) returns NULL, so cast it
                $max = (int) max($max, $value);
            }
        }

    } while (!empty($stack));

    return $max;
}

---

• This function is not actually recursive, but fulfills the requirement that it works on sub-arrays. I enjoy doing things without the runtime stack from time to time.
• It returns something of type int, never a string representation of an int. The exception is when you provide an array that does not contain any integers. It will then return NULL.
• It ignores non-array, non-int values.