On 4 Jan 2011, at 16:39, Howard Hinnant wrote:
On Jan 4, 2011, at 11:05 AM, Anthony Williams wrote:
Howard Hinnant <howard.hinnant@gmail.com> 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:
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.
I don't know. Show me the code. :-)
I am currently working on the code. I believe I am getting similar performance. However, I currently have a very heavy-duty iterator (it contains a heap-allocated array, effectively storing the stack of an algorithm like yours). Very important that it doesn't get post-incremented! Chris