#! perl -slw
use strict;
use List::Util qw[ sum ];

our $N ||= 9;

#my @data = ( 9,1,1,1,1,1,1,1,1,1 );
my @data = map{ int rand( $N ) } 1 .. $N;

my @a = @data[ 0 .. $#data / 2 ];
my @b = @data[ $#data / 2 + 1 .. $#data ];

my $diff = abs( sum( @a ) - sum( @b ) );

print "$diff : [@a] [@b]";

OUTER: for my $ai ( 0 .. $#a ) {
    for my $bi ( 0 .. $#b ) {
        if( abs(
            sum( @a[ 0 .. $ai-1, $ai+1 .. $#a ], $b[ $bi ] )
          - sum( @b[ 0 .. $bi-1, $bi+1 .. $#b ], $a[ $ai ] )
          ) < $diff
        ) {
            my $temp = $a[ $ai ];
            $a[ $ai ] = $b[ $bi ];
            $b[ $bi ] = $temp;
            $diff = abs( sum( @a ) - sum( @b ) );
            print "$diff : [@a] [@b]";
            last OUTER if $diff == 0;
        }
    }
}