Codeforces 696D Legen... AC自动机 + 矩阵快速幂

Legen...

我们能很容易写出在AC自动机上的dp， dp[ k ][ i ][ j ]表示走了 k 步从 i 走到 j 的最大值。

k 很大我们考虑矩阵优化， 直接搞就好啦。

不知道为什么在本机上M * M * M * M **** * M 打多了就会卡死不知道为什么。。。

#include<bits/stdc++.h>
#define LL long long
#define LD long double
#define ull unsigned long long
#define fi first
#define se second
#define mk make_pair
#define PLL pair<LL, LL>
#define PLI pair<LL, int>
#define PII pair<int, int>
#define SZ(x) ((int)x.size())
#define ALL(x) (x).begin(), (x).end()
#define fio ios::sync_with_stdio(false); cin.tie(0);

using namespace std;

const int N = 200 + 7;
const int inf = 0x3f3f3f3f;
const LL INF = 0x3f3f3f3f3f3f3f3f;
const int mod = 998244353;
const double eps = 1e-8;
const double PI = acos(-1);

template<class T, class S> inline void add(T& a, S b) {a += b; if(a >= mod) a -= mod;}
template<class T, class S> inline void sub(T& a, S b) {a -= b; if(a < 0) a += mod;}
template<class T, class S> inline bool chkmax(T& a, S b) {return a < b ? a = b, true : false;}
template<class T, class S> inline bool chkmin(T& a, S b) {return a > b ? a = b, true : false;}

int n, a[N];
LL l;
char s[N][N];

int MN;
struct Matrix {
    LL a[207][207];
    Matrix() {
        for(int i = 0; i < MN; i++)
            for(int j = 0; j < MN; j++)
                a[i][j] = 0;
    }
    void init() {
        for(int i = 0; i < MN; i++)
            for(int j = 0; j < MN; j++)
                a[i][j] = -INF;
    }
    Matrix operator * (const Matrix &B) const {
        Matrix C; C.init();
        for(int i = 0; i < MN; i++)
            for(int j = 0; j < MN; j++)
                for(int k = 0; k < MN; k++)
                    chkmax(C.a[i][j], a[i][k] + B.a[k][j]);
        return C;
    }
    Matrix operator ^ (LL b) {
        Matrix C = (*this);
        Matrix A = (*this);
        b--;
        while(b) {
            if(b & 1) C = C * A;
            A = A * A; b >>= 1;
        }
        return C;
    }
} M;


struct Ac { // 1. init before use  2. cheke character set
    int ch[N][26], f[N], tot, sz, subVal;
    int val[N];
    inline int newNode() {
        tot++; f[tot] = 0;
        memset(ch[tot], 0, sizeof(ch[tot]));
        return tot;
    }
    void init(int _sz, int _subVal) {
        sz = _sz; subVal = _subVal;
        tot = -1; newNode();
    }
    inline int idx(int c) {return c - subVal;}
    void addStr(char* s, int w) {
        int u = 0;
        for(int i = 0; s[i]; i++) {
            int c = idx(s[i]);
            if(!ch[u][c]) ch[u][c] = newNode();
            u = ch[u][c];
        }
        val[u] += w;
    }
    void build() {
        queue<int> que;
        for(int c = 0; c < sz; c++) {
            int v = ch[0][c];
            if(!v) ch[0][c] = 0;
            else f[v] = 0, que.push(v);
        }
        while(!que.empty()) {
            int u = que.front(); que.pop();
            val[u] += val[f[u]];
            for(int c = 0; c < sz; c++) {
                int v = ch[u][c];
                if(!v) ch[u][c] = ch[f[u]][c];
                else f[v] = ch[f[u]][c], que.push(v);
            }
        }
    }
    void getMatrix() {
        MN = tot + 1;
        for(int i = 0; i < MN; i++)
            for(int j = 0; j < MN; j++)
                M.a[i][j] = -INF;
        for(int u = 0; u <= tot; u++) {
            for(int c = 0; c < sz; c++) {
                int v = ch[u][c];
                if(!v) continue;
                chkmax(M.a[u][v], val[v]);
            }
        }
    }
} ac;

int main() {
    ac.init(26, 'a');
    scanf("%d%lld", &n, &l);
    for(int i = 1; i <= n; i++) scanf("%d", &a[i]);
    for(int i = 1; i <= n; i++) scanf("%s", s[i]);
    for(int i = 1; i <= n; i++) ac.addStr(s[i], a[i]);
    ac.build();
    ac.getMatrix();

    M = M ^ l;

    LL ans = 0;
    for(int i = 0; i < MN; i++)
        chkmax(ans, M.a[0][i]);
    printf("%lld
", ans);
    return 0;
}

/*
*/