HASH

struct Hash_map
{
    static const int mask=0x7fffff;
    int p[mask+1],q[mask+1];
    void clear()
    {
        memset(q,0,sizeof(q));
    }
    int& operator [](int k)
    {
        int i;
        for(i=k&mask;q[i]&&p[i]!=k;i=(i+1)&mask);//處理hash衝突
        p[i]=k;
        return q[i];
    }
};

// BKDR Hash Function—BYVOID
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);
}