最大流Dinic（模板）

  1 #define IOS ios_base::sync_with_stdio(0); cin.tie(0);
  2 #include <cstdio>//sprintf islower isupper
  3 #include <cstdlib>//malloc  exit strcat itoa system("cls")
  4 #include <iostream>//pair
  5 #include <fstream>//freopen("C:\\Users\\13606\\Desktop\\草稿.txt","r",stdin);
  6 #include <bitset>
  7 //#include <map>
  8 //#include<unordered_map>
  9 #include <vector>
 10 #include <stack>
 11 #include <set>
 12 #include <string.h>//strstr substr
 13 #include <string>
 14 #include <time.h>// srand(((unsigned)time(NULL))); Seed n=rand()%10 - 0~9;
 15 #include <cmath>
 16 #include <deque>
 17 #include <queue>//priority_queue<int, vector<int>, greater<int> > q;//less
 18 #include <vector>//emplace_back
 19 //#include <math.h>
 20 #include <cassert>
 21 //#include <windows.h>//reverse(a,a+len);// ~ ! ~ ! floor
 22 #include <algorithm>//sort + unique : sz=unique(b+1,b+n+1)-(b+1);+nth_element(first, nth, last, compare)
 23 using namespace std;//next_permutation(a+1,a+1+n);//prev_permutation
 24 //******************
 25 int abss(int a);
 26 int lowbit(int n);
 27 int Del_bit_1(int n);
 28 int maxx(int a,int b);
 29 int minn(int a,int b);
 30 double fabss(double a);
 31 void swapp(int &a,int &b);
 32 clock_t __STRAT,__END;
 33 double __TOTALTIME;
 34 void _MS(){__STRAT=clock();}
 35 void _ME(){__END=clock();__TOTALTIME=(double)(__END-__STRAT)/CLOCKS_PER_SEC;cout<<"Time: "<<__TOTALTIME<<" s"<<endl;}
 36 //***********************
 37 #define rint register int
 38 #define fo(a,b,c) for(rint a=b;a<=c;++a)
 39 #define fr(a,b,c) for(rint a=b;a>=c;--a)
 40 #define mem(a,b) memset(a,b,sizeof(a))
 41 #define pr printf
 42 #define sc scanf
 43 #define ls rt<<1
 44 #define rs rt<<1|1
 45 typedef vector<int> VI;
 46 typedef long long ll;
 47 const double E=2.718281828;
 48 const double PI=acos(-1.0);
 49 //const ll INF=(1LL<<60);
 50 const int inf=(1<<30);
 51 const double ESP=1e-9;
 52 const int mod=(int)1e9+7;
 53 const int N=5500;
 54 const int M=5e5+10;
 55 
 56 class DINIC
 57 {
 58 public:
 59 //    const int MAXN=10004,MAXWAY=100005;
 60     int n,way,max_flow,deep[N];
 61     int tot,head[N],cur[N];
 62     struct EDGE{
 63         int to,next;
 64         int dis;
 65     }edge[M];
 66     void Init(int n_)
 67     {
 68         tot=-1;//因为加反向边要^1,所以要从0开始;
 69         n=n_;
 70         max_flow=0;
 71         for(int i=0;i<=n_;++i)
 72             head[i]=-1;
 73     }
 74     void add(int from,int to,int V)
 75     {
 76         //正向
 77         ++tot;
 78         edge[tot].to=to;
 79         edge[tot].dis=V;
 80         edge[tot].next=head[from];
 81         head[from]=tot;
 82         //反向
 83         swap(from,to);
 84         ++tot;
 85         edge[tot].to=to;
 86         edge[tot].dis=0;
 87         edge[tot].next=head[from];
 88         head[from]=tot;
 89     }
 90     queue<int>q;
 91     bool bfs(int s,int t)
 92     {
 93         for(int i=1;i<=n;++i)
 94             deep[i]=inf;
 95         while(!q.empty())q.pop();
 96         for(int i=1;i<=n;++i)cur[i]=head[i];
 97         deep[s]=0;
 98         q.push(s);
 99 
100         while(!q.empty())
101         {
102             int now=q.front();q.pop();
103             for(int i=head[now];i!=-1;i=edge[i].next)
104             {
105                 if(deep[edge[i].to]==inf&&edge[i].dis)
106                 {
107                     deep[edge[i].to]=deep[now]+1;
108                     q.push(edge[i].to);
109                 }
110             }
111         }
112         return deep[t]<inf;
113     }
114     int dfs(int now,int t,int limit)
115     {
116         if(!limit||now==t)return limit;
117         int flow=0,f;
118         for(int i=cur[now];i!=-1;i=edge[i].next)
119         {
120             cur[now]=i;
121             if(deep[edge[i].to]==deep[now]+1&&(f=dfs(edge[i].to,t,min(limit,edge[i].dis))))
122             {
123                 flow+=f;
124                 limit-=f;
125                 edge[i].dis-=f;
126                 edge[i^1].dis+=f;
127                 if(!limit)break;
128             }
129         }
130         return flow;
131     }
132     void Dinic(int s,int t)
133     {
134         while(bfs(s,t))
135             max_flow+=dfs(s,t,inf);
136     }
137 }G;
138 int a[N][N],color[N][N];
139 
140 int main()
141 {
142     int n,m;
143     while(~sc("%d%d",&n,&m))
144     {
145         ll TOT=0;
146         for(int i=1;i<=n;++i)
147             for(int j=1;j<=m;++j)
148                 sc("%d",&a[i][j]),TOT+=a[i][j];
149         G.Init(n*m+2);
150         int S=n*m+1,T=n*m+2,cnt=0;
151         for(int i=1;i<=n;++i)
152         {
153             for(int j=1;j<=m;++j)
154             {
155                 if(i&1)
156                 {
157                     if(j&1)
158                         color[i][j]=1;
159                     else
160                         color[i][j]=0;
161                 }
162                 else
163                 {
164                     if(j&1)
165                         color[i][j]=0;
166                     else
167                         color[i][j]=1;
168                 }
169             }
170         }
171         for(int i=1;i<=n;++i)
172         {
173             for(int j=1;j<=m;++j)
174             {
175                 ++cnt;
176                 if(color[i][j]==0)
177                 {
178                     G.add(S,cnt,a[i][j]);
179                     if(i>1)G.add(cnt,cnt-m,inf);
180                     if(j>1)G.add(cnt,cnt-1,inf);
181                     if(i<n)G.add(cnt,cnt+m,inf);
182                     if(j<m)G.add(cnt,cnt+1,inf);
183                 }
184                 else
185                     G.add(cnt,T,a[i][j]);
186             }
187         }
188     /*    fo(i,1,n)
189         {
190             fo(j,1,m)
191                 pr("%d ",color[i][j]);
192             pr("\n");
193         }*/
194         G.Dinic(S,T);
195         pr("%lld\n",TOT-G.max_flow);
196     }
197     return 0;
198 }
199 
200 /**************************************************************************************/
201 
202 int maxx(int a,int b)
203 {
204     return a>b?a:b;
205 }
206 
207 void swapp(int &a,int &b)
208 {
209     a^=b^=a^=b;
210 }
211 
212 int lowbit(int n)
213 {
214     return n&(-n);
215 }
216 
217 int Del_bit_1(int n)
218 {
219     return n&(n-1);
220 }
221 
222 int abss(int a)
223 {
224     return a>0?a:-a;
225 }
226 
227 double fabss(double a)
228 {
229     return a>0?a:-a;
230 }
231 
232 int minn(int a,int b)
233 {
234     return a<b?a:b;
235 }