进制哈希

来记录一下进制哈希和比较大的模数

点击查看代码

#define ull unsigned long long
ull BKDRHash(string s){

    const ll m1 = 89999794200117649;
    const ll m2 = 999999786000011449;
    const ll m3 = 1000000000000002217;
    const ll m4 = 100000000000001921;
    ull P = 131, H = 0; // P 也可以是 13131  131313
    int n = s.size();
    for(int i = 0; i < n; i++){
        H = H*P + s[i];
    }
    return H;
}