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From: Ben Bear (benbearchen_at_[hidden])
Date: 20071114 11:18:55
some mistake or changes about partial permutation in section "Descriptions".
next_partial_permutation:
Effects: ... If such a subsequence does not exist, "it sorts the entire range".
 Change to ?: "it is back to the smallest subsequence" [Note: ..., "additionally std::reverse(first, last)".  End note]  [middle, last) MUST always be sorted, ascending order. So it should like this: "additionally std::reverse(first, last) and std::reverse(middle, last)" prev_partial_permutation: Effects: ..., "it sorts the en range in reverse order".  Change to ?: "it is back to the greatest subsequence" Postcondition: "is_sorted(rlast, rmiddle) or is_sorted(rlast, rmiddle, comp), where rlast is std::reverse_iterator(last) and rmiddle is std::reverse_iterator(middle)".  Just like next_partial_permutation, they are same, change to: "is_sorted(middle, last) or is_sorted(middle, last, comp)". [Note: ..., "additionally std::reverse(first, last)".  End note]  Change to: "additionally std::reverse(first, last) and std::reverse(middle, last)" 2007/11/14, Ben Bear <benbearchen_at_[hidden]>: > somethings that I think must be test: > > 1. count of a generating circle; > > 2. lexicographical order; > > 3. finish flag; > > 4. smallest can next() to greatest, and greatest can prev() to smallest; > > 5. next() and prev(), the state should not be changed; prev() and then > next(), too; > > 6. next generating circle should be inverted image of prev generating > circle; > > > cross test: > > 1. repetition permutation is a permutation that every element is > copied infinitude times; > > such as next_permutation(first, first + N, 0, 4) is equal: > range = {0, 0, 0, ...., 0, 1, 1, ..., 1, 2, ..., 2, 3, ..., 3} > next_permutation(range.begin(), range.begin() + N, range.end()); > > 2. completion, look up; > > > > Examples. I think should show follows about initialization: > > 1. postcondition > > 2. how to get smallest and greatest results > > Some game examples: > > Drop icons. Drop icons, then count the times of right face and wrong > face. This is a repetition combination. > > Random build a 32bit integer. Fill a 32bit integer with 0 and 1, in > random. This is repetition permutation. > > > > Hervé: > I see what your next_combination(first, last) does. I like to call it > next_combination_in_count(). Your test show that for r = 5, {0, 0, 5} > is the smallest. But I like {5, 0, 0} to be the smallest, if left is > less than right. > > I need reading the code to understand your proposal. Sorry, many > words are not clear to me. So, I edited your code... Well, my test > shows that, the main problems of your code are the finish flags. > > > The time is gone so soon... I can't write much. > > If there's anything that I should do, just ask me. I'll read, read, and > read the proposal. > > > > 2007/11/14, Hervé Brönnimann <hervebronnimann_at_[hidden]>: > > > > On Nov 13, 2007, at 10:51 PM, Ben Bear wrote: > > > Well, your next_permutation(first, last, first_value, last_value) > > > should have a little change, like this: > > > ... > > > > Ben: Your code and mine are the same. No bugs there. As for the > > file that you put on the web (your next message) I will of course > > look at it. Before we spend too much effort on the implementation, > > however, I'd advise you to read and review the proposal carefully > > first, then read the embryo of test driver that I started, and the > > examples. > > > > Once we have the test driver, we can actually verify any > > implementation we like, and I'll be in a better position to convince > > you that my implementation is correct (although it's not hard to see > > if you simply but carefully read the code). Of course, I'm always > > happy to be proven wrong  one less bug :) > > > > Check out (be advised that programs do not yet compile/run, but if > > you want to work on it or can point out problem areas, I don't see > > why not): > > > > http://photon.poly.edu/~hbr/boost/combinations.html > > http://photon.poly.edu/~hbr/boost/combination.hpp > > http://photon.poly.edu/~hbr/boost/combination_ex.cpp > > http://photon.poly.edu/~hbr/boost/combination_test.cpp > > > > Cheers, HB > > _______________________________________________ > > Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost > > >
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