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Topic: Effective implementation HashMap when keys it is foreknown

Dear colleagues, Advise what to esteem about more effective implementation HashMap (optimization on storage especially interests) when the set of keys is known in advance. In advance thanks

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Re: Effective implementation HashMap when keys it is foreknown

Hello, PrelaunchCalibration, you wrote: PC> Advise what to esteem about more effective implementation HashMap when the set of keys is known in advance. Well it is finite perfect hash function. PC> (optimization on storage especially interests) It has been proven that a general purpose minimal perfect hash scheme requires at least 1.44 bits/key. The best currently known minimal perfect hashing schemes can be represented using less than 2.1 bits/key Approximately so in practice also quits.

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Re: Effective implementation HashMap when keys it is foreknown

Hello, PrelaunchCalibration, you wrote: PC> Advise what to esteem about more effective implementation HashMap (optimization on storage especially interests) when the set of keys is known in advance. Can and is not necessary ? Time all keys are known it is possible to enumerate and use them number as an index in an array. It if typical  contains the majority of keys and it is not enough of them. Anyway for maximum efficiency achievement it is necessary  key set and their characteristic dial-ups in tables. Standard tables and so are well optimized for the general case.