常用哈希函数

int32_t BKDRHash(const std::string &name){ int32_t hash = 0, seed = 131; for (uint32_t i = 0; i < name.length(); i++){ hash = hash * seed + name[i]; //transform hash into 131 system } //to get positive number by using hash & 0111 111 111 1111b } //hash function 2 int32_t APHash(const std::string &name){ int32_t hash = 0; for (uint32_t i = 0; i < name.length(); i++){ if (i % 2){ hash ^= (~((hash << 11) ^ (name[i]) ^ (hash >> 5))); } else { hash ^= ((hash << 7) ^ (name[i]) ^ (hash >> 3)); } } return (hash & 0x7fffffff); }