my $fseq1= 'CCCCGCGC';
my @nsub1= ('CCCCG', 
             'CCCGC', 
               'CGCGC');

#produces

$result1 = [
            [ 0, 'C----' ],
            [ 1, '----C' ],
            [ 1, 'CC---' ],   # but this is extra
            [ 2, '---GC' ]
          ];