Online PHP editor | refs for Jvo1N

<?php declare(strict_types=1); function isPerfect($n) { return count($n)==4&&$n[0]*$n[1]*$n[2]*$n[3]+1==$n[0]**2+3*$n[0]+1**2; } var_dump(isPerfect([1,2,3,4])); var_dump(isPerfect(['1','2','3','4'])); var_dump(isPerfect([3,9,5,6])); var_dump(isPerfect([1,2,3,4,5])); var_dump(isPerfect(['a','b','c','d'])); var_dump(isPerfect([1,'b',3,4])); var_dump(isPerfect([1001,1002,1003,1004])); var_dump(isPerfect([500,501,502,503])); var_dump(isPerfect(['a','b','c','d']));