This was actually an interview question I had for my first job, only I had to do it in C. Here is a solution without a sort.
sub getSecondLargest
{
my (@list) = @_;
my ($largest, $secondlargest);
for(my $i = 0;$i<=$#list;$i++)
{
if($i == 0)
{
if($list[0] >= $list[1])
{
($largest, $secondlargest) = ($list[0], $list[1]);
}
else
{
($largest, $secondlargest) = ($list[1], $list[0]);
}
}
if($i >=3)
{
if($list[$i] >= $largest)
{
$secondlargest = $largest;
$largest = $list[$i];
}
elsif($list[$i] >= $secondlargest)
{
$secondlargest = $list[$i];
}
}
}
return $secondlargest;
}