Re: [boost] combinations and permutations

Subject: Re: [boost] combinations and permutations
From: Anthony Williams (anthony.ajw_at_[hidden])
Date: 2011-01-04 11:05:26

Howard Hinnant <howard.hinnant_at_[hidden]> writes:

> On Jan 4, 2011, at 6:22 AM, Christopher Jefferson wrote:
>
>> 
>> On 4 Jan 2011, at 03:40, Howard Hinnant wrote:
>> 
>>> Warming this up for tr2:
>>> 
>>> http://home.roadrunner.com/~hinnant/combinations.html
>>> 
>>> Comments welcome.  Real world use welcome.
>> 
>> For TR2, it would be nice to produce a range object, so we could write:
>> 
>> for(perm: reversible_permutation(first, mid, last) )
>>  f(perm);
>
> Not positive, but I believe (if one could figure out how to code it)
> would suffer the exponential cost of incrementation demonstrated for
> next_partial_permutation and next_combination in "Performance
> Considerations" shown in:
>
> http://home.roadrunner.com/~hinnant/combinations.html

Couldn't the range adaptor object --- or the iterators generated from it
--- store the intermediate information about where in the series of
swaps it was? Sort of a continuation in your for_each_permutation()
functions.

Anthony
-- 
Author of C++ Concurrency in Action     http://www.stdthread.co.uk/book/
just::thread C++0x thread library             http://www.stdthread.co.uk
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