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#!/usr/bin/perl
=head1
Week 132:
https://theweeklychallenge.org/blog/perl-weekly-challenge-132
Task #2: Hash Join
Write a script to implement Hash Join algorithm as suggested by wikipedia.
=cut
use strict;
use warnings;
my @player_ages = (
[20, "Alex" ],
[28, "Joe" ],
[38, "Mike" ],
[18, "Alex" ],
[25, "David" ],
[18, "Simon" ],
);
my @player_names = (
["Alex", "Stewart"],
["Joe", "Root" ],
["Mike", "Gatting"],
["Joe", "Blog" ],
["Alex", "Jones" ],
["Simon","Duane" ],
);
hash_join(\@player_ages, 1, \@player_names, 0);
sub hash_join {
my ($table_1, $key_1, $table_2, $key_2) = @_;
my $names = {
map {
join(", ", @$_) => $_->[$key_2]
} @$table_2
};
foreach my $player (@$table_1) {
my $key = $player->[$key_1];
my $age = $player->[0];
foreach my $n (keys %$names) {
if ($names->{$n} eq $key) {
print "$age, $n\n";
}
}
}
}
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