Use pthash with unordered_map about pthash HOT 4 CLOSED

You should not use a minimal perfect hash function inside a std::unordered_map.
Your pt_map vector is where your data should be stored, as indexed by pthash.
Please, read the issue you referenced: it is also explained there how to proceed.

You see, in fact, that pthash is 2X than a std::unordered_map with (essentially) optimal space usage: you only pay the cost for your data. You also have no collisions. The only downside is that a minimal perfect hash function is static by design.

Hope my explanation helps.

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Can I close this issue or do you need further help/explanation?

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I'm closing this but feel free to text me if needed.

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I think one of the issues is that pthash, like several other PMHF's, is not order-preserving.

Most PMHF's map to the range {0, 1, ..., m - 1}, but without the order-preserving property you cant really create e.g. a flat array map implementation without using an offset array, which needs at least O(mlog2(m)) bits to store

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