zz各種文字列Hash関数比較
8019 ワード
http://www.cmykrgb123.cn/blog/string-hash-compare/
Hash ELFHash，APHash ， 。
。 MD5 SHA1 ，
。
BKDRHash，APHash，DJBHash，JSHash，RSHash，SDBMHash，
PJWHash，ELFHash 。 ， 。
Hash
1
2
3
4
1
2
3
4
BKDRHash
2
0
4774
481
96.55
100
90.95
82.05
92.64
APHash
2
3
4754
493
96.55
88.46
100
51.28
86.28
DJBHash
2
2
4975
474
96.55
92.31
0
100
83.43
JSHash
1
4
4761
506
100
84.62
96.83
17.95
81.94
RSHash
1
0
4861
505
100
100
51.58
20.51
75.96
SDBMHash
3
2
4849
504
93.1
92.31
57.01
23.08
72.41
PJWHash
30
26
4878
513
0
0
43.89
0
21.95
ELFHash
30
26
4878
513
0
0
43.89
0
21.95
1 100000 。 2 100000
。 3 1 1000003( ) 。
4 1 10000019( ) 。
， 。 。 ，BKDRHash
， 。APHash 。DJBHash,JSHash,RSHash
SDBMHash 。PJWHash ELFHash ， ， 。
， ， BKDRHash 。
CmYkRgB123 ， 、 、 。
： C
unsigned int SDBMHash(char *str)
{
unsigned int hash = 0;
while (*str)
{
// equivalent to: hash = 65599*hash + (*str++);
hash = (*str++) + (hash << 6) + (hash << 16) - hash;
}
return (hash & 0x7FFFFFFF);
}
// RS Hash
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 & 0x7FFFFFFF);
}
// JS Hash
unsigned int JSHash(char *str)
{
unsigned int hash = 1315423911;
while (*str)
{
hash ^= ((hash << 5) + (*str++) + (hash >> 2));
}
return (hash & 0x7FFFFFFF);
}
// P. J. Weinberger Hash
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 & 0x7FFFFFFF);
}
// ELF Hash
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 & 0x7FFFFFFF);
}
// BKDR Hash
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 & 0x7FFFFFFF);
}
// DJB Hash
unsigned int DJBHash(char *str)
{
unsigned int hash = 5381;
while (*str)
{
hash += (hash << 5) + (*str++);
}
return (hash & 0x7FFFFFFF);
}
// AP Hash
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 & 0x7FFFFFFF);
}