#!/usr/bin/env perl 
use strict;
use warnings;

my @circles = (
    {
        x => 3.0,
        y => 10.0,
        r => 5.0
    },
    {
        x => 4.0,
        y => 9.0,
        r => 2.0
    },
    {
        x => 12.0,
        y => 4.0,
        r => 4.0
    },
);

while (my $one = shift @circles) {
    for my $other (@circles) {
        my $dx2 = ($one->{x} - $other->{x}) ** 2;
        my $dy2 = ($one->{y} - $other->{y}) ** 2;
        my $r2  = ($one->{r} + $other->{r}) ** 2;
        if ($dx2 + $dy2 < $r2) {
            warn "Potential overlap: $one->{x}, $one->{y}, $one->{r} with $other->{x}, $other->{y}, $other->{r}\n";
        }
    }
}