Hash 함수 모음

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<출처 : http://blog.daum.net/aswip/4538253>



// RS Hash Function
unsigned int RSHash(const std::string& str) { unsigned int b = 378551; unsigned int a = 63689; unsigned int hash = 0; for(std::size_t i = 0; i < str.length(); i++) { hash = hash * a + str[i]; a = a * b; } return (hash & 0x7FFFFFFF); } // JS Hash Function unsigned int JSHash(const std::string& str) { unsigned int hash = 1315423911; for(std::size_t i = 0; i < str.length(); i++) { hash ^= ((hash << 5) + str[i] + (hash >> 2)); } return (hash & 0x7FFFFFFF); } // P. J. Weinberger Hash Function unsigned int PJWHash(const std::string& str) { unsigned int BitsInUnsignedInt = (unsigned int)(sizeof(unsigned int) * 8); unsigned int ThreeQuarters = (unsigned int)((BitsInUnsignedInt * 3) / 4); unsigned int OneEighth = (unsigned int)(BitsInUnsignedInt / 8); unsigned int HighBits = (unsigned int)(0xFFFFFFFF) << (BitsInUnsignedInt - OneEighth); unsigned int hash = 0; unsigned int test = 0; for(std::size_t i = 0; i < str.length(); i++) { hash = (hash << OneEighth) + str[i]; if((test = hash & HighBits) != 0) { hash = (( hash ^ (test >> ThreeQuarters)) & (~HighBits)); } } return (hash & 0x7FFFFFFF); } // ELF Hash Function unsigned int ELFHash(const std::string& str) { unsigned int hash = 0; unsigned int x = 0; for(std::size_t i = 0; i < str.length(); i++) { hash = (hash << 4) + str[i]; if((x = hash & 0xF0000000L) != 0) { hash ^= (x >> 24); hash &= ~x; } } return (hash & 0x7FFFFFFF); } // BKDR Hash Function unsigned int BKDRHash(const std::string& str) { unsigned int seed = 131; // 31 131 1313 13131 131313 etc.. unsigned int hash = 0; for(std::size_t i = 0; i < str.length(); i++) { hash = (hash * seed) + str[i]; } return (hash & 0x7FFFFFFF); } // SDBM Hash Function unsigned int SDBMHash(const std::string& str) { unsigned int hash = 0; for(std::size_t i = 0; i < str.length(); i++) { hash = str[i] + (hash << 6) + (hash << 16) - hash; } return (hash & 0x7FFFFFFF); } // DJB Hash Function unsigned int DJBHash(const std::string& str) { unsigned int hash = 5381; for(std::size_t i = 0; i < str.length(); i++) { hash = ((hash << 5) + hash) + str[i]; } return (hash & 0x7FFFFFFF); } // DEK Hash Function unsigned int DEKHash(const std::string& str) { unsigned int hash = static_cast<unsigned int>(str.length()); for(std::size_t i = 0; i < str.length(); i++) { hash = ((hash << 5) ^ (hash >> 27)) ^ str[i]; } return (hash & 0x7FFFFFFF); } // AP Hash Function unsigned int APHash(const std::string& str) { unsigned int hash = 0; for(std::size_t i = 0; i < str.length(); i++) { hash ^= ((i & 1) == 0) ? ( (hash << 7) ^ str[i] ^ (hash >> 3)) : (~((hash << 11) ^ str[i] ^ (hash >> 5))); } return (hash & 0x7FFFFFFF); }


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