Re: [Boost-users] generate structs with all combinations of members from a given struct

Subject: Re: [Boost-users] generate structs with all combinations of members from a given struct
From: Hicham Mouline (hicham_at_[hidden])
Date: 2010-02-01 20:51:18

----- Original Message ----- 
From: "Larry Evans" <cppljevans_at_[hidden]>
To: <boost-users_at_[hidden]>
Sent: Tuesday, February 02, 2010 2:35 AM
Subject: Re: [Boost-users] generate structs with all combinations of members 
from a given struct

> On 02/01/10 03:08, Hicham Mouline wrote:
>>  ----- Original Message -----
>>     *From:* Hicham Mouline <mailto:hicham_at_[hidden]>
>>     *To:* boost-users_at_[hidden] 
>> <mailto:boost-users_at_[hidden]>
>>     *Sent:* Monday, February 01, 2010 12:09 PM
>>     *Subject:* Re: [Boost-users] generate structs with all combinations
>>     of members from a given struct
>>      My previous runtime solution was wrong.
>> I just fixed it now.
>
> I had a hard time understanding how it worked.
> A simpler solution would be to just generate the
> characteristic functions for sets of a given size.
> The characteristic function could then be used
> to select elements from the set:
>
> http://en.wikipedia.org/wiki/Characteristic_function
>
> The structure of such a program is very similar to yours
> in that it has a recursive call and a for loop.  However, with
> this method, the for loop just has size 2.  The depth of
> recursion is n, where n is size of the set.  I think your
> method had recursion depth of n-1.
>
> The attached illustrates the method.
> Output is:
>
> size=32
>  0 0 0 0 0
>  1 0 0 0 0
>  0 1 0 0 0
>  1 1 0 0 0
>  0 0 1 0 0
>  1 0 1 0 0
>  0 1 1 0 0
>  1 1 1 0 0
>  0 0 0 1 0
>  1 0 0 1 0
>  0 1 0 1 0
>  1 1 0 1 0
>  0 0 1 1 0
>  1 0 1 1 0
>  0 1 1 1 0
>  1 1 1 1 0
>  0 0 0 0 1
>  1 0 0 0 1
>  0 1 0 0 1
>  1 1 0 0 1
>  0 0 1 0 1
>  1 0 1 0 1
>  0 1 1 0 1
>  1 1 1 0 1
>  0 0 0 1 1
>  1 0 0 1 1
>  0 1 0 1 1
>  1 1 0 1 1
>  0 0 1 1 1
>  1 0 1 1 1
>  0 1 1 1 1
>  1 1 1 1 1
>
> -regards,
> Larry

Yes, all this just became clear to me last night in a dream:-)

Thanks,