Ben: On Nov 13, 2007, at 12:10 PM, Ben Bear wrote:
I think, I know what you want to do with this function:
template <class BidirectionalIterator> bool next_permutation(BidirectionalIterator first, BidirectionalIterator last, T first_value, T last_value);
I wrote a implementation, and found that it's easy :-)
In the page I whose link I gave you, that has the documentation, I guess you didn't try to click on the link named combination.hpp. I should have pointed out that the code was available. My implementation is the same in principle, but with fewer redundant tests and assignments: template <class BidirectionalIterator, class T> bool next_permutation(BidirectionalIterator first, BidirectionalIterator last, T first_value, T last_value) { while (last != first && ++(*(--last)) == last_value) { *last = first_value; } return last != first; } As for combinations, it's not much more complicated: template <class BidirectionalIterator> bool next_combination(BidirectionalIterator first, BidirectionalIterator last) { BidirectionalIterator current = last; while (current != first && *(--current) == 0) { } if (current != first) { *(--last) = --(*current); ++*(--current); } return current != first; }
[snip] Oh, your idia is beautiful :p
Glad you like it. It's simple things that work best for me :)
I think that calling this function `next_permutation' is not good. It's very different from std::next_permutation. My `next_repeat_permutation' is also not a good name, because only I call it `repeat_permutation'.
The question of names is a good one. There is room for rationales, in the documentation page: I would have put something there about using the same name. There is no "partial" about it, this time, and I didn't have any problems naming it permutations since the signatures can't possibly be ambiguous. But perhaps a different name is a good idea. At heart, it's an assignment of values from [first,last) to [first_value, last_value). So next_assignment would be a possibility. Also since the relationship is functional, next_function or next_mapping would be possible. next_one_to_many_assignment or next_one_to_many_mapping is more precise, but too long IMHO. I don't really like any of those alternatives. It's a permutation with repetitions, but next_repetition or next_permutation_with_repetition isn't good either... In the end, I don't have anything better than next_permutation. let's hear some more suggestions... -- HB