https://www.hackerrank.com/challenges/ctci-array-left-rotation/

array-left-rotation.php

<?php

$arr = [1,2,3,4,5];
$d = 4;

var_dump(rotLeft($arr, $d));

function rotLeft($a, $d) {
    if (gettype($a) !== 'array' || !count($a)) {
        return [];
    }
    if (gettype($d) !== 'integer' || $d <= 0 || !($d % count($a)) ) {
        return $a;
    }
    
    while ($d--) {
        $n = reset($a);
        unset($a[key($a)]);
        array_push($a, $n);
    }
    
    return $a;
}

?>