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-;
 const double pi = acos(-1.0);
 const double inf = ~0u>>;
 const int child_num = ;
 char vir[][];
 string o[][N];
 class AC
 {
     private:
     int ch[N][child_num];
     int fail[N];
     int Q[N];
     int val[N];
     int sz;
     int id[];
     int dp[][N];
     char s[N];
     public:
     void init()
     {
         fail[] = ;
         for(int i =  ; i < child_num ;i++)
         id[i+'a'] = i;
     }
     void reset()
     {
         memset(ch[],,sizeof(ch[]));
         memset(val,,sizeof(val));
         sz = ;
     }
     void insert(char *a,int key)
     {
         int p = ;
         for(; *a ; a++)
         {
             int d= id[*a];
             if(ch[p][d]==)
             {
                 memset(ch[sz],,sizeof(ch[sz]));
                 s[sz] = *a;
                 ch[p][d] = sz++;
             }
             p = ch[p][d];
         }
         val[p] = key;
     }
     void construct()
     {
         int i,head=,tail = ;
         for(i = ; i  < child_num ;i++)
         {
             if(ch[][i])
             {
                 fail[ch[][i]] = ;
                 Q[tail++] = ch[][i];
             }
         }
         while(head!=tail)
         {
             int u = Q[head++];
             val[u]+=val[fail[u]];
             for(i = ; 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 =  ; i <= n ;i++)
             for(j =  ;j < sz ; j++)
             {
                 dp[i][j] = -INF;
                 o[i][j].clear();
             }
         dp[][] = ;
         for(i = ; i < n ;i++)
         {
             for(j =  ; j < sz ; j++)
             for(g =  ; g < child_num ; g++)
             {
                 int tv = dp[i][j]+val[ch[j][g]];
                 if(dp[i+][ch[j][g]] <= tv)
                 {
                     if(dp[i+][ch[j][g]]<tv||o[i+][ch[j][g]]>o[i][j]+char(g+'a'))
                     o[i+][ch[j][g]] = o[i][j]+char(g+'a');
                     dp[i+][ch[j][g]] = dp[i][j]+val[ch[j][g]];
                 }
             }
         }
         int ans = ,y=,x=;
         for(i =  ; i <=n ;i++)
             for(j = ;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 = ;
         if(ans==) 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 = ;i <= m ;i++)
         scanf("%s",vir[i]);
         for(i = ; i <= m ;i++)
         {
             int v;
             scanf("%d",&v);
             ac.insert(vir[i],v);
         }
         ac.construct();
         ac.work(n);
     }
     return ;
 }