hdu3247Resource Archiver（ac自动机+spfa)

链接

这题没想到怎么做，问了下p队长，大悟。。

先求出任意两串的在trie树上的最短距离，期间是不能走到不合法的地方，我是用spfa求得，在更新和加入节点时判断一下是不是合法位置。

求出最短距离之后，找出一条从0出发遍历所有串的最短距离，可以dp出，dp[i][j]表示当前状态以节点j串结尾的最短距离。

枚举一下最后结尾的为哪一个串时距离最短。

 #include <iostream>
 #include<cstdio>
 #include<cstring>
 #include<algorithm>
 #include<stdlib.h>
 #include<vector>
 #include<cmath>
 #include<queue>
 #include<set>
 using namespace std;
 #define N 60010
 #define M 10010
 #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 = ;
 int w[][];
 bool vis[N];
 int dis[N];
 class AC
 {
     private:
     int ch[N][child_num];
     int fail[N];
     int Q[N];
     int val[N],vv[N];
     int id[];
     int sz ;
     int po[];
     int dp[][];
     public:
     void init()
     {
         fail[] = ;
         id[''] = ;
         id[''] = ;
     }
     void reset()
     {
         memset(ch[],,sizeof(ch[]));
         memset(val,,sizeof(val));
         memset(vv,,sizeof(vv));
         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]));
                 ch[p][d] = sz++;
             }
             p = ch[p][d];
         }
         if(key!=-)
         {
             val[p] = <<(key-);
             po[key] = p;
         }
         else
         {
             vv[p] = ;
         }
     }
     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++];
             vv[u]|=vv[fail[u]];
             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];
             }
         }
     }
     int spfa(int st,int ed)
     {
         int i;
         memset(vis,,sizeof(vis));
         for(i = ; i <= sz ;i++)
         dis[i] = INF;
         dis[st] = ;
         vis[st] = ;
         queue<int>q;
         q.push(st);
         while(!q.empty())
         {
             int u = q.front();
             q.pop();
             for(i =  ; i < child_num; i++)
             {
                 int v = ch[u][i];
                 if(vv[v]) continue;
                 dis[v] = min(dis[v],dis[u]+);
                 //if(st == 4&&ed==8)
                 //cout<<v<<" "<<dis[v]<<" "<<u<<endl;
                 if(!vis[v])
                 {
                     vis[v] = ;
                     q.push(v);
                 }
             }
         }
         return dis[ed];
     }
     void find_dis(int n)
     {
         int i,j;
         po[] = ;
         for(i = ; i <= n ;i++)
         {
             w[][i] = w[i][] = spfa(,po[i]);
             //cout<<w[0][i]<<endl;
         }
         for(i = ; i <= n; i++)
             for(j =  ; j <= n ;j++)
             {
                 w[i][j] = spfa(po[i],po[j]);
                // cout<<w[i][j]<<" "<<i<<" "<<j<<endl;
             }
     }
     void work(int n)
     {
         int i,j,g;
         for(i =  ; i < (<<n) ; i++)
             for(j = ;j <= n; j++)
             dp[i][j] = INF;
         dp[][] = ;
         for(i =  ;i < (<<n) ; i++)
         {
             for(j =  ;j <= n ;j++)
             {
                 for(g =  ; g <= n ;g++)
                 {
                     if((<<(g-))&i) continue;
                     dp[i+(<<(g-))][g] = min(dp[i+(<<(g-))][g],dp[i][j]+w[j][g]);
                 }
             }
         }
         int ans = INF;
         for(i =  ; i <= n ; i++)
         ans = min(ans,dp[(<<n)-][i]);
         cout<<ans<<endl;
     }
 }ac;
 char vir[],re[];
 int main()
 {
     int n,m,i;
     ac.init();
     while(scanf("%d%d",&n,&m)&&n&&m)
     {
         ac.reset();
         for(i = ; i <= n ;i++)
         {
             scanf("%s",re);
             ac.insert(re,i);
         }
         while(m--)
         {
             scanf("%s",vir);
             ac.insert(vir,-);
         }
         ac.construct();
         ac.find_dis(n);
         ac.work(n);
     }
     return ;
 }