use strict;

my @CATEGORY  = ("USA", "CANADA" , "EUROPE" , "TAIWAN");
my @FOOD      = ("PIZZA" , "MAPLE" , "EURO" , "INDEPENDENCE");
my @FILENAMES = ("MAPLESTEA.txt" , "HOTPIZZA.txt" , "EURODOLLAR.txt");
my %HASH;


my %aux;
@aux{@FOOD} = @CATEGORY;

LINE:
foreach my $file (@FILENAMES) {
    foreach (sort {length($b) <=> length($a)} keys %aux) {
        if ($file =~ /\Q$_\E/) {
            $HASH{$aux{$_}}{$file} = 1;
            next LINE;
        }
    }
}

use Data::Dumper;
print Dumper(\%HASH);
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