use strict;

my %hash1;
my %hash2;

my @data = (0 .. 5000);

for (my $i = 0; $i < scalar(@data); $i++ ) {
        for (my $j = $i; $j < scalar(@data); $j++) {
                $hash1{ $data[$i] }{ $data[$j] } = 0;
                $hash2{ $data[$i] }{ $data[$j] } = 0;
                }
        }


while ( my ($key1, $val1) = each %hash1 ) {
        while ( my ($key2, $val2) = each %$val1 ) {
                print join(
                        "\t",
                        $key1,
                        $key2,
                        $hash1{$key1}{$key2},
                        $hash2{$key1}{$key2}
                        ), "\n";
                }
        }

##</code><code>##

use strict;

my %hash1;
my %hash2;
my %hash3;

my @data = (0 .. 5000);

for (my $i = 0; $i < scalar(@data); $i++ ) {
        for (my $j = $i; $j < scalar(@data); $j++) {
                $hash1{ $data[$i] }{ $data[$j] } = 0;
                $hash2{ $data[$i] }{ $data[$j] } = 0;
                $hash3{ $data[$i] }{ $data[$j] } = 0;
                }
        }

print "Finished building hashes\n";

while ( my ($key1, $val1) = each %hash1 ) {
        while ( my ($key2, $val2) = each %$val1 ) {
                print join(
                        "\t",
                        $key1,
                        $key2,
                        $hash1{$key1}{$key2},
                        $hash2{$key1}{$key2},
                        $hash3{$key1}{$key2}
                        ), "\n";
                }
        }

##</code><code>##

use strict;

my %hash1;
my %hash2;
my %hash3;

my @data = (0 .. 5000);

for (my $i = 0; $i < scalar(@data); $i++ ) {
        for (my $j = $i; $j < scalar(@data); $j++) {
                $hash1{ $data[$i] }{ $data[$j] } = 0;
                $hash2{ $data[$i] }{ $data[$j] } = 0;
                $hash3{ $data[$i] }{ $data[$j] } = 0;
                }
        }

print "Finished building hashes\n";

while ( my ($key1, $val1) = each %hash1 ) {
        while ( my ($key2, $val2) = each %$val1 ) {
                print join(
                        "\t",
                        $key1,
                        $key2,
                        $hash1{$key1}{$key2},
                        $hash2{$key1}{$key2},
                        $hash3{$key1}{$key2}
                        ), "\n";
                }
        delete $hash1{$key1};
        delete $hash2{$key1};
        delete $hash3{$key1};
        }