常见的Hash函数 Hash Function HashFunction hash

郑承恩

2023-12-01

hash functions

#define M 249997
#define M1 1000001
#define M2 0xF0000000

// RS Hash Function
unsigned int RSHash(char*str)
{
    unsigned int b=378551 ;
    unsigned int a=63689 ;
    unsigned int hash=0 ;

    while(*str)
    {
        hash=hash*a+(*str++);
        a*=b ;
    }

    return(hash % M);
}

// JS Hash Function
unsigned int JSHash(char*str)
{
    unsigned int hash=1315423911 ; // 这个不是质数，能被3整除，为什么要用这个数?

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

    return(hash % M);
}

function isPrime(num) {
	if (num == 2 || num == 3) {
		return true;
	}
	if (num % 6 !== 1 && num % 6 !== 5) {
		return false;
	}
	for (var i = 5; i * i <= num; i += 6) {
		if (num % i == 0 || num % (i+2) == 0) {
			return false;
		}
	}
	return true;
}

// P. J. Weinberger Hash Function
unsigned int PJWHash(char*str)
{
    unsigned int BitsInUnignedInt=(unsigned int)(sizeof(unsigned int)*8);
    unsigned int ThreeQuarters=(unsigned int)((BitsInUnignedInt*3)/4);
    unsigned int OneEighth=(unsigned int)(BitsInUnignedInt/8);
    unsigned int HighBits=(unsigned int)(0xFFFFFFFF)<<(BitsInUnignedInt-OneEighth);
    unsigned int hash=0 ;
    unsigned int test=0 ;

    while(*str)
    {
        hash=(hash<<OneEighth)+(*str++);
        if((test=hash&HighBits)!=0)
        {
            hash=((hash^(test>>ThreeQuarters))&(~HighBits));
        }
    }

    return(hash % M);
}

// ELF Hash Function
unsigned int ELFHash(char*str)
{
    unsigned int hash=0 ;
    unsigned int x=0 ;

    while(*str)
    {
        hash=(hash<<4)+(*str++);
        if((x=hash&0xF0000000L)!=0)
        {
            hash^=(x>>24);
            hash&=~x ;
        }
    }

    return(hash % M);
}

// BKDR Hash Function
unsigned int BKDRHash(char*str)
{
    unsigned int seed=131 ;// 31 131 1313 13131 131313 etc..
    unsigned int hash=0 ;

    while(*str)
    {
        hash=hash*seed+(*str++);
    }

    return(hash % M);
}

// SDBM Hash Function
unsigned int SDBMHash(char*str)
{
    unsigned int hash=0 ;

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

    return(hash % M);
}

// DJB Hash Function
unsigned int DJBHash(char*str)
{
    unsigned int hash=5381 ;

    while(*str)
    {
        hash+=(hash<<5)+(*str++);
    }

    return(hash % M);
}

// AP Hash Function
unsigned int APHash(char*str)
{
    unsigned int hash=0 ;
    int i ;

    for(i=0;*str;i++)
    {
        if((i&1)==0)
        {
            hash^=((hash<<7)^(*str++)^(hash>>3));
        }
        else
        {
            hash^=(~((hash<<11)^(*str++)^(hash>>5)));
        }
    }

    return(hash % M);
}

/**
* Hash算法大全<br>
* 推荐使用FNV1算法
* @algorithm None
* @author Goodzzp 2006-11-20
* @lastEdit Goodzzp 2006-11-20
* @editDetail Create
*/
public class HashAlgorithms
{
/**
* 加法hash
* @param key 字符串
* @param prime 一个质数
* @return hash结果
*/
public static int additiveHash(String key, int prime)
{
   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
*/
public static int rotatingHash(String key, int prime)
{
   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
*/
static int M_MASK = 0x8765fed1;
/**
* 一次一个hash
* @param key 输入字符串
* @return 输出hash值
*/
public static int oneByOneHash(String key)
{
   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
*/
public static int bernstein(String key)
{
   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; ++i)
//     hash=tab[hash^key[i]];
//   return (hash);
// }

CRC Hashing，计算crc,具体代码见其他
// ub4 crc(char *key, ub4 len, ub4 mask, ub4 tab[256])
// {
//   ub4 hash, i;
//   for (hash=len, i=0; i<len; ++i)
//     hash = (hash >> 8) ^ tab[(hash & 0xff) ^ key[i]];
//   return (hash & mask);
// }

/**
* Universal Hashing
*/
public static int universal(char[]key, int mask, int[] tab)
{
   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
*/
public static int zobrist( char[] key,int mask, int[][] tab)
{
   int hash, i;
   for (hash=key.length, i=0; i<key.length; ++i)
     hash ^= tab[i][key[i]];
   return (hash & mask);
}

// LOOKUP3
// 见Bob Jenkins(3).c文件

// 32位FNV算法
static int M_SHIFT = 0;
/**
* 32位的FNV算法
* @param data 数组
* @return int值
*/
    public static int FNVHash(byte[] data)
    {
        int hash = (int)2166136261L;
        for(byte b : data)
            hash = (hash * 16777619) ^ b;
        if (M_SHIFT == 0)
            return hash;
        return (hash ^ (hash >> M_SHIFT)) & M_MASK;
    }
    /**
     * 改进的32位FNV算法1
     * @param data 数组
     * @return int值
     */
    public static int FNVHash1(byte[] data)
    {
        final int p = 16777619;
        int hash = (int)2166136261L;
        for(byte b:data)
            hash = (hash ^ b) * p;
        hash += hash << 13;
        hash ^= hash >> 7;
        hash += hash << 3;
        hash ^= hash >> 17;
        hash += hash << 5;
        return hash;
    }
    /**
     * 改进的32位FNV算法1
     * @param data 字符串
     * @return int值
     */
    public static int FNVHash1(String data)
    {
        final int p = 16777619;
        int hash = (int)2166136261L;
        for(int i=0;i<data.length();i++)
            hash = (hash ^ data.charAt(i)) * p;
        hash += hash << 13;
        hash ^= hash >> 7;
        hash += hash << 3;
        hash ^= hash >> 17;
        hash += hash << 5;
        return hash;
    }

    /**
     * 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..
        int hash = 0;

       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);
       return hash;
    }
    /* End Of AP Hash Function */

    /**
     * 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;
     }
---------------------
作者：HQD因为有趣所以做题
来源：CSDN
原文：https://blog.csdn.net/hqd_acm/article/details/5901955
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常见的Hash函数 Hash Function HashFunction hash

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