use strict;
use warnings;

use Time::HiRes qw/time/;

my ( @data1, @data2 );
push @data1, [rand(10), rand(10), rand(10), rand(10)] for 1 .. 100_000;
push @data2, [rand(10), rand(10), rand(10), rand(10)] for 1 ..     100;

for my $point2 ( @data2 ) {
    my %nearest = (
        distance => 1_000_000,
        point    => [0,0,0,0],
    );
    for my $point1 ( @data1 ) {
        next if abs( $point1->[0] - $point2->[0] ) > $nearest{distance};
        next if abs( $point1->[1] - $point2->[1] ) > $nearest{distance};
        next if abs( $point1->[2] - $point2->[2] ) > $nearest{distance};
        next if abs( $point1->[3] - $point2->[3] ) > $nearest{distance};
        my $distance = sqrt(
            ($point1->[0]-$point2->[0]) ** 2 +
            ($point1->[1]-$point2->[1]) ** 2 +
            ($point1->[2]-$point2->[2]) ** 2 +
            ($point1->[3]-$point2->[3]) ** 2
        );
        if ( $distance < $nearest{distance} ) {
            $nearest{distance} = $distance;
            $nearest{point   } = [ @$point1 ];
        }
    }
    #print $nearest{distance} . "\n";
}