dancing link模板

  1 #include<cstdio>

  2 #include<iostream>

  3 #include<cstring>

  4 #include<algorithm>

  5 #include<cmath>

  6 #include<iomanip> 

  7 using namespace std;

  8 

  9 const int n=729,m=324;

 10 bool mx[2000][2000];//数独转化过来的01矩阵 

 11 int map[10][10],cnt[2000],head,cur,ans;

 12 int sqr[10][10]={{0,0,0,0,0,0,0,0,0,0},  //九宫格的编号 

 13                {0,1,1,1,4,4,4,7,7,7},

 14                {0,1,1,1,4,4,4,7,7,7},

 15                {0,1,1,1,4,4,4,7,7,7},

 16                {0,2,2,2,5,5,5,8,8,8},

 17                {0,2,2,2,5,5,5,8,8,8},

 18                {0,2,2,2,5,5,5,8,8,8},

 19                {0,3,3,3,6,6,6,9,9,9},

 20                {0,3,3,3,6,6,6,9,9,9},

 21                {0,3,3,3,6,6,6,9,9,9}};

 22 

 23 int w[10][10]={{0,0,0,0,0,0,0,0,0,0},

 24                {0,6,6,6,6,6,6,6,6,6},

 25                {0,6,7,7,7,7,7,7,7,6},

 26                {0,6,7,8,8,8,8,8,7,6},

 27                {0,6,7,8,9,9,9,8,7,6},

 28                {0,6,7,8,9,10,9,8,7,6},

 29                {0,6,7,8,9,9,9,8,7,6},

 30                {0,6,7,8,8,8,8,8,7,6},

 31                {0,6,7,7,7,7,7,7,7,6},

 32                {0,6,6,6,6,6,6,6,6,6}};

 33                

 34 struct point

 35 {

 36     int row,lc,rc,up,down,col;//元素的上下左右,行号和列标 

 37 }node[2000*2000];

 38 

 39 inline int id(int x,int y)

 40 {

 41     return (x-1)*9+y;//格子(x,y)的编号 

 42 }

 43 

 44 void init(int c)//初始化列标元素 

 45 {

 46     for (int i=0;i<=c;i++)

 47     {

 48         node[i].lc=i-1;

 49         node[i].rc=i+1;

 50         node[i].up=node[i].down=node[i].col=i;

 51     }

 52     node[0].lc=c;

 53     node[c].rc=0;

 54 }

 55 

 56 void build_link()//把01矩阵中的 1 用dancing link 连接 

 57 {

 58     cur=m;

 59     for (int i=1;i<=n;i++)

 60     {

 61         int start,pre;

 62         start=pre=cur+1;

 63         for (int j=1;j<=m;j++)

 64             if (mx[i][j])

 65             {

 66                 cur++;

 67                 cnt[j]++;

 68                 node[cur].row=i;

 69                 

 70                 node[cur].lc=pre;

 71                 node[cur].rc=start;

 72                 node[pre].rc=cur;

 73                 node[start].lc=cur;

 74                 

 75                 node[cur].col=j;

 76                 node[cur].up=node[j].up;

 77                 node[cur].down=j;

 78                 node[node[j].up].down=cur;

 79                 node[j].up=cur;

 80                 pre=cur;

 81             }

 82     }

 83 }

 84 

 85 inline void cover(int c)//删除冲突元素 

 86 {

 87     for (int i=node[c].up;i!=c;i=node[i].up)

 88         for (int j=node[i].rc;j!=i;j=node[j].rc)

 89         {

 90             node[node[j].up].down=node[j].down;

 91             node[node[j].down].up=node[j].up;

 92             cnt[node[j].col]--;

 93         }

 94     node[node[c].lc].rc=node[c].rc;

 95     node[node[c].rc].lc=node[c].lc;

 96 }

 97 

 98 inline void uncover(int c)//恢复冲突元素 

 99 {

100     for (int i=node[c].up;i!=c;i=node[i].up)

101         for (int j=node[i].rc;j!=i;j=node[j].rc)

102         {

103             node[node[j].up].down=j;

104             node[node[j].down].up=j;

105             cnt[node[j].col]++;

106         }

107     node[node[c].lc].rc=c;

108     node[node[c].rc].lc=c;

109 }

110 

111 void read_data()//把数独转化成01矩阵 

112 {

113     for (int i=1;i<=9;i++)

114         for (int j=1;j<=9;j++)

115         {

116             scanf("%d",&map[i][j]);

117             int c=id(i,j),t,k;

118             if (map[i][j])//数独中本来有数,直接加入 

119             {

120                 k=map[i][j];

121                 t=(c-1)*9+k;

122                 mx[t][c]=true;

123                 mx[t][81+9*(i-1)+k]=true;

124                 mx[t][162+9*(j-1)+k]=true;

125                 mx[t][243+(sqr[i][j]-1)*9+k]=true;

126             }

127             else 

128             {

129                 for (k=1;k<=9;k++) //数独中本来没数,那么加入1-9的情况 

130                 {

131                     t=(c-1)*9+k;

132                     mx[t][c]=true;

133                     mx[t][81+9*(i-1)+k]=true;

134                     mx[t][162+9*(j-1)+k]=true;

135                     mx[t][243+(sqr[i][j]-1)*9+k]=true;

136                 }

137             }

138         }

139 }

140 

141 bool dfs(int step,int score)

142 {

143     if (node[head].rc==head) //已经全部覆盖 

144     {

145         ans=max(score,ans);

146         return true;

147     }

148     

149     int i,j,c,t=210000,x,y,num,flag=0;

150     for (i=node[head].rc;i!=head;i=node[i].rc) //启发式,每次处理元素最少的列 

151         if (cnt[i]<t)

152         {

153             t=cnt[i];

154             c=i;

155         }

156     if (t==0)

157         return false;

158         

159     cover(c);//覆盖当前列 

160     

161     for (i=node[c].down;i!=c;i=node[i].down)

162     {

163         for (j=node[i].lc;j!=i;j=node[j].lc)//删除冲突的行 

164             cover(node[j].col);

165         num=(node[i].row-1)/9+1;

166         x=(num-1)/9+1;

167         y=num-9*(x-1);

168         flag|=dfs(step+1,score+w[x][y]*(node[i].row-(num-1)*9));

169         for (j=node[i].rc;j!=i;j=node[j].rc)//恢复删除冲突的行 

170             uncover(node[j].col);

171     }

172     

173     uncover(c);//恢复当前列 

174     return flag;

175 }

176 

177 void solve()

178 {

179     init(m);

180     build_link();

181     int flag=1;

182     if (!dfs(1,0))

183         printf("-1\n");

184     else printf("%d\n",ans);

185 }

186 

187 int main()

188 {

189     read_data();

190     solve();

191     return 0;

192 } 

 

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