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combinations: count
and size_hint
#729
combinations: count
and size_hint
#729
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Because we give combinations in the lexicographic order, we can use the indices to count the remaining combinations to come. We are gonna heavily test it thought.
The whole point of the lazy buffer is to not fill the pool all at once but in some cases we want to, and then it's better than do it with `while lazy_buffer.get_next() {}` that would be weird.
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Hi @Philippe-Cholet I tried to review, and I have some questions.
I think the most difficult part for me is to understand remaining_for
.
`pool.it.count()` consumes `pool` before we call `remaining_for` so it can not be a method and therefore becomes a free function.
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Thanks for the update. We should comment the sources for the complex algorithms and add some tests, then I think we're good to go.
And add todo
Only test for `n <= 500` but only a few values of the last row do not already have overflow on a 64 bits computer. NOTE: Not faster with an array updated in-place.
All changes are done (with a limit of 500 for Ready to squash everything into one commit. |
The indices we track (to give combinations in the lexicographic order) can help us count the remaining combinations.
@phimuemue That's all for combinations. Each commit is as small as possible. Similar work for other iterators to come, but this should be the biggest as it prepares work for
powerset
andcombinations_with_replacement
.