数组中去除重复序列，哈希表用法

#!/usr/bin/perl
use strict;
my %hash;
my @array = (1..10,5,20,2,3,4,5,5);
#grep 保存符合条件的元素
@array = grep { ++$hash{$_} < 2 } @array;
print join(" ",@array);
print "\n";