multidimensional array min max

<?php 
session_start();
include 'config.php';
$post = $_GET['post'];
$slected = array();
		if(isset($_POST['checkb'])){
			if(count($_POST['sa']) > 0){			
				$do2 = mysql_query("UPDATE ptable SET status='updated' WHERE id='$post'") or die(mysql_error());
				if($do2){
				echo 'updated';
				}
				foreach($_POST['sa'] as $awrd) {
		
				$result = mysql_query("UPDATE ctable SET awarded='yes' WHERE id='$awrd'") or die(mysql_error());
			   		$slected[] = $awrd;
					if($result){
					echo 'awarded'.$usersid;
					}
				}		
			}			
		} else{
$result = mysql_query("SELECT status FROM ptable WHERE id=$post") or die(mysql_error());
while ($row = mysql_fetch_array($result))
{
$status=$row['status'];
}
if($status!='updated'){
?>   
<form method="post" name="formk" action="<?= $_SERVER['PHP_SELF']. '?' . $_SERVER['QUERY_STRING'] ?>">
<?php
$result = mysql_query("SELECT cid, iqid, cost, usersid FROM ctable WHERE post=$post");
while ($row = mysql_fetch_array($result))
{
  $arr[$row['iqid']][$row['usersid']] = $row['cost'];
  $arr2[$row['iqid']][$row['usersid']] = $row['cid'];
  $uid[] = $row['usersid'];
}
$uid = array_unique($uid);
$qid = array_keys($arr);

$query = "SELECT MIN(cost), MAX(cost) FROM ctable WHERE post=$post"; 
$result = mysql_query($query) or die(mysql_error());
while($row = mysql_fetch_array($result)){
	$min=$row['MIN(cost)'];
	$max=$row['MAX(cost)'];
}
echo '<table><tr><td></td>';
foreach($uid as $userid) echo "<td>$userid</td>";
echo '</tr>';
foreach($qid as $iqid)
{
  echo "<tr><td>$iqid</td>";
  foreach($uid as $userid)
  {
	if (isset($arr[$iqid][$userid]))
	{
		if($min==$arr[$iqid][$userid]){
		echo "<td bgcolor=\"#FFFF00\">".$arr[$iqid][$userid]."<input type='checkbox' name='sa[]' value='{$arr2[$iqid][$userid]}'></td>";
		}else if($max==$arr[$iqid][$userid]){
		echo "<td bgcolor=\"#00FF00\">".$arr[$iqid][$userid]."<input type='checkbox' name='sa[]' value='{$arr2[$iqid][$userid]}'></td>";
		}else{
		echo "<td>".$arr[$iqid][$userid]."<input type='checkbox' name='sa[]' value='{$arr2[$iqid][$userid]}'></td>";
		}
	}
	else echo "<td></td>";	
  }
  echo "</tr>";
}
echo '</table>';
echo '<input type="submit" name="checkb" />';
 echo'</form>';	
}
}
?>

PHP:

i want the lowest cost in every iqid to have background color #FF0000
any help would be appreciated..