字符串哈希模板

先贴个板子，日后再理解

typedef unsigned long long ull;
const int N = 100000 + 5;
const ull base = 163;
char s[N];
ull hash[N];

void init(){//处理hash值
    p[0] = 1;
    hash[0] = 0;
    int n = strlen(s + 1);
   for(int i = 1; i <=100000; i ++)p[i] =p[i-1] * base;
   for(int i = 1; i <= n; i ++)hash[i] = hash[i - 1] * base + (s[i] - 'a');
}

ull get(int l, int r, ull g[]){//取出g里l - r里面的字符串的hash值
    return g[r] - g[l - 1] * p[r - l + 1];
}