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。

  1 #include <iostream>

  2 #include<cstdio>

  3 #include<cstring>

  4 #include<algorithm>

  5 #include<stdlib.h>

  6 #include<vector>

  7 #include<cmath>

  8 #include<queue>

  9 #include<set>

 10 #include<string>

 11 using namespace std;

 12 #define N 1105

 13 #define LL long long

 14 #define INF 0xfffffff

 15 const double eps = 1e-8;

 16 const double pi = acos(-1.0);

 17 const double inf = ~0u>>2;

 18 const int child_num = 26;

 19 char vir[110][15];

 20 string o[55][N];

 21 class AC

 22 {

 23     private:

 24     int ch[N][child_num];

 25     int fail[N];

 26     int Q[N];

 27     int val[N];

 28     int sz;

 29     int id[128];

 30     int dp[55][N];

 31     char s[N];

 32     public:

 33     void init()

 34     {

 35         fail[0] = 0;

 36         for(int i = 0 ; i < child_num ;i++)

 37         id[i+'a'] = i;

 38     }

 39     void reset()

 40     {

 41         memset(ch[0],0,sizeof(ch[0]));

 42         memset(val,0,sizeof(val));

 43         sz = 1;

 44     }

 45     void insert(char *a,int key)

 46     {

 47         int p = 0;

 48         for(; *a ; a++)

 49         {

 50             int d= id[*a];

 51             if(ch[p][d]==0)

 52             {

 53                 memset(ch[sz],0,sizeof(ch[sz]));

 54                 s[sz] = *a;

 55                 ch[p][d] = sz++;

 56             }

 57             p = ch[p][d];

 58         }

 59         val[p] = key;

 60     }

 61     void construct()

 62     {

 63         int i,head=0,tail = 0;

 64         for(i = 0; i  < child_num ;i++)

 65         {

 66             if(ch[0][i])

 67             {

 68                 fail[ch[0][i]] = 0;

 69                 Q[tail++] = ch[0][i];

 70             }

 71         }

 72         while(head!=tail)

 73         {

 74             int u = Q[head++];

 75             val[u]+=val[fail[u]];

 76             for(i = 0; i < child_num ; i++)

 77             {

 78                 if(ch[u][i])

 79                 {

 80                     fail[ch[u][i]] = ch[fail[u]][i];

 81                     Q[tail++] = ch[u][i];

 82                 }

 83                 else ch[u][i] = ch[fail[u]][i];

 84             }

 85         }

 86     }

 87     void work(int n)

 88     {

 89         int i,j,g;

 90         for(i = 0 ; i <= n ;i++)

 91             for(j = 0 ;j < sz ; j++)

 92             {

 93                 dp[i][j] = -INF;

 94                 o[i][j].clear();

 95             }

 96         dp[0][0] = 0;

 97         for(i = 0; i < n ;i++)

 98         {

 99             for(j = 0 ; j < sz ; j++)

100             for(g = 0 ; g < child_num ; g++)

101             {

102                 int tv = dp[i][j]+val[ch[j][g]];

103                 if(dp[i+1][ch[j][g]] <= tv)

104                 {

105                     if(dp[i+1][ch[j][g]]<tv||o[i+1][ch[j][g]]>o[i][j]+char(g+'a'))

106                     o[i+1][ch[j][g]] = o[i][j]+char(g+'a');

107                     dp[i+1][ch[j][g]] = dp[i][j]+val[ch[j][g]];

108                 }

109             }

110         }

111         int ans = 0,y=0,x=0;

112         for(i = 0 ; i <=n ;i++)

113             for(j =0 ;j < sz ; j++)

114             {

115                 if(ans<=dp[i][j])

116                 {

117                     if(ans<dp[i][j]||(y==i&&o[i][j]<o[i][x]))

118                     {

119                         ans = dp[i][j];

120                         y = i;

121                         x = j;

122                     }

123                 }

124             }

125         g = 0;

126         if(ans==0) puts("");

127         else

128         cout<<o[y][x]<<endl;

129     }

130 }ac;

131 int main()

132 {

133     int n,i,m,t;

134     ac.init();

135     cin>>t;

136     while(t--)

137     {

138         scanf("%d%d",&n,&m);

139         ac.reset();

140         for(i = 1;i <= m ;i++)

141         scanf("%s",vir[i]);

142         for(i = 1; i <= m ;i++)

143         {

144             int v;

145             scanf("%d",&v);

146             ac.insert(vir[i],v);

147         }

148         ac.construct();

149         ac.work(n);

150     }

151     return 0;

152 }

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