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gperf is an open source C and C++ perfect hash generator (very fast, but only works for small sets) Minimal Perfect Hashing (bob algorithm) by Bob Jenkins; cmph: C Minimal Perfect Hashing Library, open source implementations for many (minimal) perfect hashes (works for big sets) Sux4J: open source monotone minimal perfect hashing in Java
Name Length Type Pearson hashing: 8 bits (or more) XOR/table Paul Hsieh's SuperFastHash [1]: 32 bits Buzhash: variable XOR/table Fowler–Noll–Vo hash function
A mid-squares hash code is produced by squaring the input and extracting an appropriate number of middle digits or bits. For example, if the input is 123 456 789 and the hash table size 10 000, then squaring the key produces 15 241 578 750 190 521, so the hash code is taken as the middle 4 digits of the 17-digit number (ignoring the high digit ...
C++11 includes unordered_map in its standard library for storing keys and values of arbitrary types. [51] Go's built-in map implements a hash table in the form of a type. [52] Java programming language includes the HashSet, HashMap, LinkedHashSet, and LinkedHashMap generic collections. [53] Python's built-in dict implements a hash table in the ...
Often this is done by first building a cryptographically secure pseudorandom number generator and then using its stream of random bytes as keystream. SEAL is a stream cipher that uses SHA-1 to generate internal tables, which are then used in a keystream generator more or less unrelated to the hash algorithm. SEAL is not guaranteed to be as ...
MurmurHash is a non-cryptographic hash function suitable for general hash-based lookup. [1] [2] [3] It was created by Austin Appleby in 2008 [4] and, as of 8 January 2016, [5] is hosted on GitHub along with its test suite named SMHasher.
The lookup3 function consumes input in 12 byte (96 bit) chunks. [9] It may be appropriate when speed is more important than simplicity. Note, though, that any speed improvement from the use of this hash is only likely to be useful for large keys, and that the increased complexity may also have speed consequences such as preventing an optimizing compiler from inlining the hash function.
A rolling hash (also known as recursive hashing or rolling checksum) is a hash function where the input is hashed in a window that moves through the input.. A few hash functions allow a rolling hash to be computed very quickly—the new hash value is rapidly calculated given only the old hash value, the old value removed from the window, and the new value added to the window—similar to the ...