1、 常用的字符串Hash函數(shù)還有ELFHash,APHash等等,都是十分簡單有效的方法。這些函數(shù)使用位運算使得每一個字符都對最后的函數(shù)值產(chǎn)生影響。另外還有以MD5 常用字符串哈希函數(shù)有BKDRHash,APHash,DJBHash,JSHash,RSHash, SDBMHash,PJWHash,ELFHash等等。對于以上幾種哈希函數(shù),我對其進行了 其中數(shù)據(jù)1為100000個字母和數(shù)字組成的隨機串哈希沖突個數(shù)。數(shù)據(jù)2為100000個有意義的英文句子哈希沖突個數(shù)。數(shù)據(jù)3為數(shù)據(jù)1的哈希值與1000003(大素數(shù)求模后存儲到線性表中沖突的個數(shù)。數(shù)據(jù)4為數(shù)據(jù)1的哈希值與10000019(更大素數(shù)求模后

2、存儲到線性表中沖突的個數(shù)。經(jīng)過比較,得出以上平均得分。平均數(shù)為平方平均數(shù)?？梢园l(fā)現(xiàn),BKDRHash無論是在實際效果還是編碼實現(xiàn)中,效果都是最突出的。APHash也是較為優(yōu)秀的算法。DJBHash,JSHash,RSHash與SDBMHash各有千秋。PJWHash與ELFHash效果最差,但得分相似,其算法本質(zhì)是相似的。在信息修競賽中,要本著易于編碼調(diào)試的原則,個人認為BKDRHash是最適合記憶和使用的。BYVoid原創(chuàng),歡迎建議、交流、批評和指正。附:各種哈希函數(shù)的C語言程序代碼 / equivalent to: hash = 65599*hash + (*str+;hash =(*st

3、r+(hash 6+(hash 16- hash;return(hash &0x7FFFFFFF;/ RS Hash Functionunsigned int RSHash(char*strunsigned int b =378551;unsigned int a =63689;unsigned int hash =0;while(*strhash = hash * a +(*str+;a *= b;return(hash &0x7FFFFFFF;/ JS Hash Functionunsigned int JSHash(char*strunsigned int hash =131542391

4、1;while(*strhash =(hash 2;return(hash &0x7FFFFFFF;/ P. J. Weinberger Hash Functionunsigned int PJWHash(char*strunsigned int BitsInUnignedInt =(unsigned int(sizeof(unsigned int* 8;unsigned int ThreeQuarters =(unsigned int(BitsInUnignedInt *3/4;unsigned int OneEighth =(unsigned int(BitsInUnignedInt /

5、8;unsigned int HighBits =(unsigned int(0xFFFFFFFF (BitsInUnignedInt - OneEighth;unsigned int hash =0;unsigned int test =0;while(*strhash =(hash ThreeQuarters&(HighBits;return(hash &0x7FFFFFFF;/ ELF Hash Functionunsigned int ELFHash(char*strunsigned int hash =0;unsigned int x =0;while(*strhash =(hash

6、 24;hash &= x;return(hash &0x7FFFFFFF;/ BKDR Hash Functionunsigned int BKDRHash(char*strunsigned int seed =131;/ 31 131 1313 13131 131313 etc.unsigned int hash =0;while(*strhash = hash * seed +(*str+;return(hash &0x7FFFFFFF;/ DJB Hash Functionunsigned int DJBHash(char*strunsigned int hash =5381;while(*strhash +=(hash 5+(*str+;return(hash &0x7FFFFFFF;/ AP Hash Functionunsigned int APHash(char*strunsigned i