邝斌的ACM模板（字符串 HASH）

本博客整理自邝斌的ACM模板
1.7、字符串 HASH
HDU4622 求区间不相同子串个数

const int HASH = 10007;const int MAXN = 2010;struct HASHMAP{    int head[HASH],next[MAXN],size;    unsigned long long state[MAXN];    int f[MAXN];    void init()    {        size = 0;        memset(head,-1,sizeof(head));    }    int insert(unsigned long long val,int _id)    {        int h = val%HASH;        for(int i = head[h]; i != -1; i = next[i])            if(val == state[i])            {                int tmp = f[i];                f[i] = _id;                return tmp;            }        f[size] = _id;        state[size] = val;        next[size] = head[h];        head[h] = size++;        return 0;    }} H;const int SEED = 13331;unsigned long long P[MAXN];unsigned long long S[MAXN];char str[MAXN];int ans[MAXN][MAXN];int main(){    //freopen("in.txt","r",stdin);    //freopen("out.txt","w",stdout);    P[0] = 1;    for(int i = 1; i < MAXN; i++)        P[i] = P[i-1] * SEED;    int T;    scanf("%d",&T);    while(T--)    {        scanf("%s",str);        int n = strlen(str);        S[0] = 0;        for(int i = 1; i <= n; i++)            S[i] = S[i-1]*SEED + str[i-1];        memset(ans,0,sizeof(ans));        for(int L = 1; L <= n; L++)        {            H.init();            for(int i = 1; i + L - 1 <= n; i++)            {                int l = H.insert(S[i+L-1] - S[i-1]*P[L],i);                ans[i][i+L-1] ++;                ans[l][i+L-1]--;            }        }        for(int i = n; i >= 0; i--)            for(int j = i; j <= n; j++)                ans[i][j] += ans[i+1][j] + ans[i][j-1] - ans[i+1][j-1];        int m,u,v;        scanf("%d",&m);        while(m--)        {            scanf("%d%d",&u,&v);            printf("%d\n",ans[u][v]);        }    }    return 0;}