Seriously, there may be easier solutions, (Set::IntSpan).

This way involves the vec function.

#!/usr/bin/perl
use strict;
use warnings;
use List::Util qw/ min max /;

my @range = ([5,15], [2, 20]);

my $min = min map {$_->[0]} @range;
my $max = max map {$_->[1]} @range;

my @vec = ("") x @range;

for my $i (0 .. $#vec) {
    vec($vec[$i], $_, 1) = 1 for $range[$i][0] .. $range[$i][1];    
}

my $overlap = shift @vec;
$overlap &= $vec[ $_ ] for 0 .. $#vec;

my $count;
for my $offset ($min .. $max) {
    ++$count if vec($overlap, $offset, 1) == 1;
}

print $count;
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My problem is I can't think of the mathematical algorithm in order to check the overlap between the two ranges of numbers.

You do know how to whistle don't you?

overlap range

overlap range

site:perlmonks.org overlap range

site:search.cpan.org overlap range

Number::Range

overlap between ranges

Range overlap (with a lot of ranges)

You could use Set::IntSpan:

use Set::IntSpan;

my $r1 = Set::IntSpan->new([ 5 .. 15 ]);
my $r2 = Set::IntSpan->new([ 2 .. 20 ]);

my $i = $r1->intersect($r2);

if ( !$i->empty and ( $i->max - $i->min ) >= 5 ) # criteria
{
    print "hit\n";
}
else
{
    print "miss\n";
}
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Please see comments

#!/usr/bin/perl 

my $val=0;
my @array_a = (1..8);
my @array_b = (6..10);
my %count= ();
my @all = ();
my @inter =();
my @different =();

foreach $val (@array_a, @array_b) { $count{$val}++; } #build hash 
# that counts the number of times a number is seen
# 1=>1, 2=>1, ... 6=>2, 7=>2, etc...

foreach $val (keys %count) {

    push @all, $val; # the keys have to be unique in hash %count
 
    push @{ $count{$val} > 1 ? \@inter : \@different}, $val;  # lookup
+ ternary operator
# if the $val of %count is  >1 push to @inter. if not, push to @differ
+ent
};

@all = sort {$a <=> $b} @all;    #sort
@different = sort {$a <=> $b} @different;
@inter = sort {$a <=> $b} @inter;

print "all:\n";
foreach (@all) {
    print "\t$_\n";    
};

print "Different:\n";
foreach (@different) {
    print "\t$_\n";    
};

print "Intersect:\n";
foreach (@inter) {
    print "\t$_\n";    
};
[download]

HTH, Rob

Oh be nice!