++ hash算法大全
/**
- Hash算法大全
- 推荐使用FNV1算法
- @algorithm None
- @author Goodzzp 2006-11-20
- @lastEdit Goodzzp 2006-11-20
- @editDetail Create
- /
- 加法hash
- @param key 字符串
- @param prime 一个质数
- @return hash结果
- /
int hash, i;
for (hash = key.length(), i = 0; i < key.length(); i++)
hash += key.charAt(i);
return (hash % prime);
}
/**
- 旋转hash
- @param key 输入字符串
- @param prime 质数
- @return hash值
- /
int hash, i;
for (hash=key.length(), i=0; i<key.length(); ++i)
hash = (hash<<4)^(hash>>28)^key.charAt(i);
return (hash % prime);
// return (hash ^ (hash>>10) ^ (hash>>20));
}
// 替代：
// 使用：hash = (hash ^ (hash>>10) ^ (hash>>20)) & mask;
// 替代：hash %= prime;
/**
- MASK值，随便找一个值，最好是质数
- /
- 一次一个hash
- @param key 输入字符串
- @return 输出hash值
- /
int hash, i;
for (hash=0, i=0; i<key.length(); ++i)
{
hash += key.charAt(i);
hash += (hash << 10);
hash ^= (hash >> 6);
}
hash += (hash << 3);
hash ^= (hash >> 11);
hash += (hash << 15);
// return (hash & M_MASK);
return hash;
}
/**
- Bernstein's hash
- @param key 输入字节数组
- @param level 初始hash常量
- @return 结果hash
- /
int hash = 0; int i; for (i=0; i<key.length(); ++i) hash = 33*hash + key.charAt(i); return hash;
}
//
//// Pearson's Hash
// char pearson(char[]key, ub4 len, char tab[256])
// {
// char hash;
// ub4 i;
// for (hash=len, i=0; i<len; hash="tab[hash^key[i]];" (hash="len," i="0;"></len;> 8) ^ tab[(hash];
// return (hash & mask);
// }
/**
- Universal Hashing
- /
int hash = key.length, i, len = key.length;
for (i=0; i<(len<<3); i+=8)
{
char k = key[i>>3];
if ((k&0x01) == 0) hash ^= tab[i+0];
if ((k&0x02) == 0) hash ^= tab[i+1];
if ((k&0x04) == 0) hash ^= tab[i+2];
if ((k&0x08) == 0) hash ^= tab[i+3];
if ((k&0x10) == 0) hash ^= tab[i+4];
if ((k&0x20) == 0) hash ^= tab[i+5];
if ((k&0x40) == 0) hash ^= tab[i+6];
if ((k&0x80) == 0) hash ^= tab[i+7];
}
return (hash & mask);
}
/**
- Zobrist Hashing
- /
/**
* Thomas Wang的算法，整数hash
*/
public static int intHash(int key)
{
key += ~(key << 15);
key ^= (key >>> 10);
key += (key << 3);
key ^= (key >>> 6);
key += ~(key << 11);
key ^= (key >>> 16);
return key;
}
/**
* RS算法hash
* @param str 字符串
*/
public static int RSHash(String str)
{
int b = 378551;
int a = 63689;
int hash = 0;
for(int i = 0; i < str.length(); i++)
{
hash = hash * a + str.charAt(i);
a = a * b;
}
return (hash & 0x7FFFFFFF);
}
/* End Of RS Hash Function */
/**
* JS算法
*/
public static int JSHash(String str)
{
int hash = 1315423911;
for(int i = 0; i < str.length(); i++)
{
hash ^= ((hash << 5) + str.charAt(i) + (hash >> 2));
}
return (hash & 0x7FFFFFFF);
}
/* End Of JS Hash Function */
/**
* PJW算法
*/
public static int PJWHash(String str)
{
int BitsInUnsignedInt = 32;
int ThreeQuarters = (BitsInUnsignedInt * 3) / 4;
int OneEighth = BitsInUnsignedInt / 8;
int HighBits = 0xFFFFFFFF << (BitsInUnsignedInt - OneEighth);
int hash = 0;
int test = 0;
for(int i = 0; i < str.length();i++)
{
hash = (hash << OneEighth) + str.charAt(i);
if((test = hash & HighBits) != 0)
{
hash = (( hash ^ (test >> ThreeQuarters)) & (~HighBits));
}
}
return (hash & 0x7FFFFFFF);
}
/* End Of P. J. Weinberger Hash Function */
/**
* ELF算法
*/
public static int ELFHash(String str)
{
int hash = 0;
int x = 0;
for(int i = 0; i < str.length(); i++)
{
hash = (hash << 4) + str.charAt(i);
if((x = (int)(hash & 0xF0000000L)) != 0)
{
hash ^= (x >> 24);
hash &= ~x;
}
}
return (hash & 0x7FFFFFFF);
}
/* End Of ELF Hash Function */
/**
* BKDR算法
*/
public static int BKDRHash(String str)
{
int seed = 131; // 31 131 1313 13131 131313 etc..
for(int i = 0; i < str.length(); i++)
{
hash = (hash * seed) + str.charAt(i);
}
return (hash & 0x7FFFFFFF);
}
/* End Of BKDR Hash Function */
/**
* SDBM算法
*/
public static int SDBMHash(String str)
{
int hash = 0;
for(int i = 0; i < str.length(); i++)
{
hash = str.charAt(i) + (hash << 6) + (hash << 16) - hash;
}
return (hash & 0x7FFFFFFF);
}
/* End Of SDBM Hash Function */
/**
* DJB算法
*/
public static int DJBHash(String str)
{
int hash = 5381;
for(int i = 0; i < str.length(); i++)
{
hash = ((hash << 5) + hash) + str.charAt(i);
}
return (hash & 0x7FFFFFFF);
}
/* End Of DJB Hash Function */
/**
* DEK算法
*/
public static int DEKHash(String str)
{
int hash = str.length();
for(int i = 0; i < str.length(); i++)
{
hash = ((hash << 5) ^ (hash >> 27)) ^ str.charAt(i);
}
return (hash & 0x7FFFFFFF);
}
/* End Of DEK Hash Function */
/**
* AP算法
*/
public static int APHash(String str)
{
int hash = 0;
for(int i = 0; i < str.length(); i++)
{
hash ^= ((i & 1) == 0) ? ( (hash << 7) ^ str.charAt(i) ^ (hash >> 3)) :
(~((hash << 11) ^ str.charAt(i) ^ (hash >> 5)));
}
// return (hash & 0x7FFFFFFF);
/**
* JAVA自己带的算法
*/
public static int java(String str)
{
int h = 0;
int off = 0;
int len = str.length();
for (int i = 0; i < len; i++)
{
h = 31 * h + str.charAt(off++);
}
return h;
}
/**
* 混合hash算法，输出64位的值
*/
public static long mixHash(String str)
{
long hash = str.hashCode();
hash <<= 32;
hash |= FNVHash1(str);
return hash;
}