3 ms·

> then I would mark it very low. What would you do differently? I would also assert if any overlapping intervals were inserted - it’s an invariant. If it was

> then I would mark it very low. What would you do differently? I would also assert if any overlapping intervals were inserted - it’s an invariant. If it was static I would just sort and binary search, but with inserts this seems like a fine way to reuse the std::map. Std templates are designed for this kind of thing - make a custom comparator, document why it works, wrap it in a typedef.

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AlotOfReading 1y ago
This is one of those cases where being able to name the problem helps. It's a discrete interval problem and is typically solved by a discrete interval tree. Diets are a particularly clever solution to this: https://web.engr.oregonstate.edu/~erwig/diet/ https://web.engr.oregonstate.edu/~erwig/diet/
- monkeyelite 1y ago
  That’s the same idea as putting intervals in map, an ordered tree.
derriz 1y ago
Unless you know about the internal implementation of std::map, then abusing the ordering function (which is expected be a total order according to the std::map documentation - i.e. capable of comparing any two elements of the key space) to throw exception when the API for std::map is used in a way you want to block - is not a robust solution. This will probably work but there’s nothing that constrains std::map to be implemented as a RB tree. Nor is it intuitive - given it relies on understanding how balanced trees are typically implemented. An “optimized” implementation of std::map should be entitled, for example, to cache results of previous comparisons and exploit the transitive rule for total orders to avoid unnecessarily performing comparisons. Then this solution breaks. I know whining about downvotes is frowned upon here but I’m surprised to having lost karma here. I’m making what I believe is a good faith argument and am happy to debate my position.
- monkeyelite 1y ago
  > internal implementation of std::map > abusing the ordering function That's the thing about C++. It's not abuse - any strict weak ordering is valid. You are follow the rules and it's guaranteed mathematically to produce correct results. > capable of comparing any two elements of the key space You get to define the domain of keys which is almost always a restriction of the possible bits of the key. For example, you can use floats as keys even though nan would break. > Nor is it intuitive Intuitive too often means "I haven't seen it before" which is a bias to not learn new approaches of programming. All sufficiently technical knowledge is unintuitive. - it relies on understanding how balanced trees are typically implemented. No it doesn't. It's documented API. > exploit the transitive rule for total orders to avoid unnecessarily performing comparisons Yes, the comparison must satisfy transitivity. This doesn't violate that. > I know whining about downvotes is frowned upon here I downvote low-quality, not to disagree (I did not downvote).

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AlotOfReading 1y ago

This is one of those cases where being able to name the problem helps. It's a discrete interval problem and is typically solved by a discrete interval tree. Diets are a particularly clever solution to this: https://web.engr.oregonstate.edu/~erwig/diet/ https://web.engr.oregonstate.edu/~erwig/diet/

monkeyelite 1y ago
That’s the same idea as putting intervals in map, an ordered tree.

derriz 1y ago

Unless you know about the internal implementation of std::map, then abusing the ordering function (which is expected be a total order according to the std::map documentation - i.e. capable of comparing any two elements of the key space) to throw exception when the API for std::map is used in a way you want to block - is not a robust solution. This will probably work but there’s nothing that constrains std::map to be implemented as a RB tree. Nor is it intuitive - given it relies on understanding how balanced trees are typically implemented. An “optimized” implementation of std::map should be entitled, for example, to cache results of previous comparisons and exploit the transitive rule for total orders to avoid unnecessarily performing comparisons. Then this solution breaks. I know whining about downvotes is frowned upon here but I’m surprised to having lost karma here. I’m making what I believe is a good faith argument and am happy to debate my position.

monkeyelite 1y ago
> internal implementation of std::map > abusing the ordering function That's the thing about C++. It's not abuse - any strict weak ordering is valid. You are follow the rules and it's guaranteed mathematically to produce correct results. > capable of comparing any two elements of the key space You get to define the domain of keys which is almost always a restriction of the possible bits of the key. For example, you can use floats as keys even though nan would break. > Nor is it intuitive Intuitive too often means "I haven't seen it before" which is a bias to not learn new approaches of programming. All sufficiently technical knowledge is unintuitive. - it relies on understanding how balanced trees are typically implemented. No it doesn't. It's documented API. > exploit the transitive rule for total orders to avoid unnecessarily performing comparisons Yes, the comparison must satisfy transitivity. This doesn't violate that. > I know whining about downvotes is frowned upon here I downvote low-quality, not to disagree (I did not downvote).