#!/usr/bin/perl
use strict;
use warnings;
use List::Util 'sum';

my @set = (3, 2, 8, 9, -25, 5, 8, 4, 4, -3, 5, 3, -10);
pop   @set while $set[-1] < 0;
shift @set while $set[0]  < 0;

my @neg = map {$set[$_] < 0 ? $_ : () } 0 .. $#set;
my @beg = (0, map {$_ + 1} @neg);
my @end = ($#set, map {$_ - 1} @neg);
my ($beg, $end, $max, $sum) = (0) x 4;

for my $i (@beg) {
    for my $j (@end) {
        next if $j < $i;
        $sum = sum(@set[$i .. $j]);
        ($beg, $end, $max) = ($i, $j, $sum) if $sum > $max;
    }
}
# Adjust accordingly if leading/trailing negatives
print "$beg .. $end = $max\n";