Re: Strange Bitmapset manipulation in DiscreteKnapsack()

David Rowley <dgrowleyml@gmail.com> writes:

> On Fri, 19 Jan 2024 at 01:07, Andy Fan <zhihuifan1213@163.com> wrote:
>> I find the following code in DiscreteKnapsack is weird.
>>
>>
>>         for (i = 0; i <= max_weight; ++i)
>>         {
>>                 values[i] = 0;
>>
>> ** memory allocation here, and the num_items bit is removed later **
>>
>>                 sets[i] = bms_make_singleton(num_items);
>>         }
>>
>>
>>         ** num_items bit is removed here **
>>         result = bms_del_member(bms_copy(sets[max_weight]), num_items);
>
> It does not seem weird to me.  If the set is going to have multiple
> words then adding a member 1 higher than the highest we'll ever add
> ensures the set has enough words and we don't need to repalloc to grow
> the set when we bms_add_member().

Hmm, I missed this part, thanks for the explaination. If bitset feature
can get in someday, the future user case like this can use bitset
directly to avoid this trick method. 

-- 
Best Regards
Andy Fan