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购买衣裤算法c语言,常用Hash算法(C语言的简单实现)

#include "GeneralHashFunctions.h"

unsigned int RSHash(char* str, unsigned int len)

{

unsigned int b = 378551;

unsigned int a = 63689;

unsigned int hash = 0;

unsigned int i = 0;

for(i = 0; i < len; str++, i++)

{

hash = hash * a + (*str);

a = a * b;

}

return hash;

}

unsigned int JSHash(char* str, unsigned int len)

{

unsigned int hash = 1315423911;

unsigned int i = 0;

for(i = 0; i < len; str++, i++)

{

hash ^= ((hash << 5) + (*str) + (hash >> 2));

}

return hash;

}

unsigned int PJWHash(char* str, unsigned int len)

{

const unsigned int BitsInUnsignedInt = (unsigned int)(sizeof(unsigned int) * 8);

const unsigned int ThreeQuarters = (unsigned int)((BitsInUnsignedInt * 3) / 4);

const unsigned int OneEighth = (unsigned int)(BitsInUnsignedInt / 8);

const unsigned int HighBits = (unsigned int)(0xFFFFFFFF) << (BitsInUnsignedInt - OneEighth);

unsigned int hash = 0;

unsigned int test = 0;

unsigned int i = 0;

for(i = 0; i < len; str++, i++)

{

hash = (hash << OneEighth) + (*str);

if((test = hash & HighBits) != 0)

{

hash = (( hash ^ (test >> ThreeQuarters)) & (~HighBits));

}

}

return hash;

}

unsigned int ELFHash(char* str, unsigned int len)

{

unsigned int hash = 0;

unsigned int x = 0;

unsigned int i = 0;

for(i = 0; i < len; str++, i++)

{

hash = (hash << 4) + (*str);

if((x = hash & 0xF0000000L) != 0)

{

hash ^= (x >> 24);

}

hash &= ~x;

}

return hash;

}

unsigned int BKDRHash(char* str, unsigned int len)

{

unsigned int seed = 131;

unsigned int hash = 0;

unsigned int i = 0;

for(i = 0; i < len; str++, i++)

{

hash = (hash * seed) + (*str);

}

return hash;

}

unsigned int SDBMHash(char* str, unsigned int len)

{

unsigned int hash = 0;

unsigned int i = 0;

for(i = 0; i < len; str++, i++)

{

hash = (*str) + (hash << 6) + (hash << 16) - hash;

}

return hash;

}

unsigned int DJBHash(char* str, unsigned int len)

{

unsigned int hash = 5381;

unsigned int i = 0;

for(i = 0; i < len; str++, i++)

{

hash = ((hash << 5) + hash) + (*str);

}

return hash;

}

unsigned int DEKHash(char* str, unsigned int len)

{

unsigned int hash = len;

unsigned int i = 0;

for(i = 0; i < len; str++, i++)

{

hash = ((hash << 5) ^ (hash >> 27)) ^ (*str);

}

return hash;

}

unsigned int BPHash(char* str, unsigned int len)

{

unsigned int hash = 0;

unsigned int i = 0;

for(i = 0; i < len; str++, i++)

{

hash = hash << 7 ^ (*str);

}

return hash;

}

unsigned int FNVHash(char* str, unsigned int len)

{

const unsigned int fnv_prime = 0x811C9DC5;

unsigned int hash = 0;

unsigned int i = 0;

for(i = 0; i < len; str++, i++)

{

hash *= fnv_prime;

hash ^= (*str);

}

return hash;

}

unsigned int APHash(char* str, unsigned int len)

{

unsigned int hash = 0xAAAAAAAA;

unsigned int i = 0;

for(i = 0; i < len; str++, i++)

{

hash ^= ((i & 1) == 0) ? ( (hash << 7) ^ (*str) * (hash >> 3)) :

(~((hash << 11) + ((*str) ^ (hash >> 5))));

}

return hash;

}