#! perl -slw
use strict;
use List::Util qw[ reduce ]; $a = $b; ## silence warning

sub weightedSum {
    my( $r, $weight ) = ( @_, 1 );
    return reduce{
        $a += ( ref( $b ) ) ? weightedSum( $b, $weight + 1 ): $b * $weight
    } 0, @$r;
}

my $arrref = [
    [1,1,1,1],
    [1,1, [2,2] ],
    [1, [2, [3,3] ] ]
];

print weightedSum( $arrref );