Hash模板 个人模板

/**
 * Hash模板
 * Based: 0
 * template<unsigned long _SZ,class _T, unsigned long *pFun(_T _Off)>
 * class _My_Hash_ToInt
 * 传入数据大小_SZ,传入类型_T,Hash函数
 * 传入类型_T必须重载 = 和 == 符号
 * 收录了ELFHash函数
 * 主要是为了判重的简化些的模板
 * Hash算法性能比较见 http://www.cnblogs.com/lonelycatcher/archive/2011/08/23/2150587.html
 */

const long hashsize = 51071; //Hash表大小(注意修改)
// 各种Hash算法
unsigned int SDBMHash(char *str)
{
    unsigned int hash = hashsize;

    while (*str)
    {
        // equivalent to: hash = 65599*hash + (*str++);
        hash = (*str++) + (hash << 6) + (hash << 16) - hash;
    }

    return (hash & 0x7FFFFFFF);
}

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

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

    return (hash & 0x7FFFFFFF);
}

// JS Hash Function
unsigned int JSHash(char *str)
{
    unsigned int hash = 1315423911;

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

    return (hash & 0x7FFFFFFF);
}

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

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

    return (hash & 0x7FFFFFFF);
}

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

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

    return (hash & 0x7FFFFFFF);
}

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

// 程序模板
template<typename _T>
class _My_Hash_ToInt_Data
{
public:
    _My_Hash_ToInt_Data()
    {
        times = 0;
        next = -1;
    }
    _T data;
    long times;
    long next;
};
template<long _SZ,class _T, unsigned long pFun(_T& _Off)>
class _My_Hash_ToInt
{
public:
    _My_Hash_ToInt()
    {
        memset(hash, -1, sizeof(hash));
        length = 0;
    };
    ~_My_Hash_ToInt(){};
    long find(_T _Off)
    {
        long pos = hash[pFun(_Off)];
        while(pos >= 0)
        {
            if(data[pos].data == _Off)
                return pos;
            else
                pos = data[pos].next;
        }
        return -1;
    }
    long insert(_T _Off)
    {
        long oldPos = pFun(_Off);
        long pos = hash[oldPos];
        while(pos >= 0)
        {
            if(data[pos].data == _Off)
            {
                data[pos].times ++;
                return pos;
            }
            else
                pos = data[pos].next;
        }
        data[length].data = _Off;
        data[length].times = 1;
        data[length].next = hash[oldPos];
        hash[oldPos] = length ;
        return length ++;
    }
    void clear()
    {
        length = 0;
        memset(hash, -1, sizeof(hash));
        memset(data, -1, sizeof(data));
    }
    //Member
    long length;
    _My_Hash_ToInt_Data<_T> data[_SZ];
    long hash[hashsize];
};

//节点类（注意修改）
class node
{
public:
    char str[60];
    bool operator == (node &strin)
    {
        return !strcmp(str, strin.str);
    }
    node& operator = (node &strin)
    {
        strcpy(str, strin.str);
        return (*this);
    }
};
//扩展Hash函数（注意修改）
unsigned long ELFHashEx(node &strIn)
{
    return ELFHash(strIn.str);
}
_My_Hash_ToInt<10005, node, ELFHashEx>hash;//Hash类例子