<?php
function check($s)
{ $open =  ['(', '[', '{', '<'];
  $close = [')', ']', '}', '>'];
  $stack = array();
  for ($j=0; $j<strlen($s); $j++)
  { if        (in_array($s[$j],$open))  array_push($stack, $s[$j]);
    else { if (in_array($s[$j],$close))
           { if (count($stack) == 0) return false;
             for ($k=0; $k<4; $k++) if ($close[$k]==$s[$j]) break;
             if ($stack[count($stack)-1] == $open[$k]) array_pop($stack);
             else return false;
           }
         }
  }  
  return (count($stack) == 0);
}
if (check('[{([[[<>]]])(<>)(){}}]'))  echo "true \n"; else echo "false \n"; // true
if (check(']()(){<>}[[()]]'))         echo "true \n"; else echo "false \n"; // false
if (check('[(sjd),"2"],{2:3}, [<>]')) echo "true \n"; else echo "false \n"; // true
if (check('{[[[[((()))]]<]>]}'))      echo "true \n"; else echo "false \n"; // false
?>