hdu2296Ring（ac自动机+dp)

链接

dp[i][j]表示长度为i在节点J的时候的权值最大值，根据trie树转移一下就行，需要每次都取最小的，所以需要另开一数组保存字典序最小的状态。

#include <iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<stdlib.h>
#include<vector>
#include<cmath>
#include<queue>
#include<set>
#include<string>
using namespace std;
#define N 1105
#define LL long long
#define INF 0xfffffff
const double eps = 1e-8;
const double pi = acos(-1.0);
const double inf = ~0u>>2;
const int child_num = 26;
char vir[110][15];
string o[55][N];
class AC
{
    private:
    int ch[N][child_num];
    int fail[N];
    int Q[N];
    int val[N];
    int sz;
    int id[128];
    int dp[55][N];
    char s[N];
    public:
    void init()
    {
        fail[0] = 0;
        for(int i = 0 ; i < child_num ;i++)
        id[i+'a'] = i;
    }
    void reset()
    {
        memset(ch[0],0,sizeof(ch[0]));
        memset(val,0,sizeof(val));
        sz = 1;
    }
    void insert(char *a,int key)
    {
        int p = 0;
        for(; *a ; a++)
        {
            int d= id[*a];
            if(ch[p][d]==0)
            {
                memset(ch[sz],0,sizeof(ch[sz]));
                s[sz] = *a;
                ch[p][d] = sz++;
            }
            p = ch[p][d];
        }
        val[p] = key;
    }
    void construct()
    {
        int i,head=0,tail = 0;
        for(i = 0; i  < child_num ;i++)
        {
            if(ch[0][i])
            {
                fail[ch[0][i]] = 0;
                Q[tail++] = ch[0][i];
            }
        }
        while(head!=tail)
        {
            int u = Q[head++];
            val[u]+=val[fail[u]];
            for(i = 0; i < child_num ; i++)
            {
                if(ch[u][i])
                {
                    fail[ch[u][i]] = ch[fail[u]][i];
                    Q[tail++] = ch[u][i];
                }
                else ch[u][i] = ch[fail[u]][i];
            }
        }
    }
    void work(int n)
    {
        int i,j,g;
        for(i = 0 ; i <= n ;i++)
            for(j = 0 ;j < sz ; j++)
            {
                dp[i][j] = -INF;
                o[i][j].clear();
            }
        dp[0][0] = 0;
        for(i = 0; i < n ;i++)
        {
            for(j = 0 ; j < sz ; j++)
            for(g = 0 ; g < child_num ; g++)
            {
                int tv = dp[i][j]+val[ch[j][g]];
                if(dp[i+1][ch[j][g]] <= tv)
                {
                    if(dp[i+1][ch[j][g]]<tv||o[i+1][ch[j][g]]>o[i][j]+char(g+'a'))
                    o[i+1][ch[j][g]] = o[i][j]+char(g+'a');
                    dp[i+1][ch[j][g]] = dp[i][j]+val[ch[j][g]];
                }
            }
        }
        int ans = 0,y=0,x=0;
        for(i = 0 ; i <=n ;i++)
            for(j =0 ;j < sz ; j++)
            {
                if(ans<=dp[i][j])
                {
                    if(ans<dp[i][j]||(y==i&&o[i][j]<o[i][x]))
                    {
                        ans = dp[i][j];
                        y = i;
                        x = j;
                    }
                }
            }
        g = 0;
        if(ans==0) puts("");
        else
        cout<<o[y][x]<<endl;
    }
}ac;
int main()
{
    int n,i,m,t;
    ac.init();
    cin>>t;
    while(t--)
    {
        scanf("%d%d",&n,&m);
        ac.reset();
        for(i = 1;i <= m ;i++)
        scanf("%s",vir[i]);
        for(i = 1; i <= m ;i++)
        {
            int v;
            scanf("%d",&v);
            ac.insert(vir[i],v);
        }
        ac.construct();
        ac.work(n);
    }
    return 0;
}