不知道为啥坠大点权独立集的做法跟最大权闭合图差不多?
qwq
#include<cstdio> #include<cstring> #include<cctype> #include<algorithm> #include<cstdlib> #include<queue> #define maxn 30000 using namespace std; inline long long read(){ long long num=0,f=1; char ch=getchar(); while(!isdigit(ch)){ if(ch=='-') f=-1; ch=getchar(); } while(isdigit(ch)){ num=num*10+ch-'0'; ch=getchar(); } return num*f; } int n,m; inline int count(int i){ return i&1?i+1:i-1; } inline int calc(int x,int y){ return (x-1)*m+y; } struct Edge{ int next,to,val; }edge[maxn*5]; int head[maxn],num; inline void addedge(int from,int to,int val){ edge[++num]=(Edge){head[from],to,val}; head[from]=num; } inline void add(int from,int to,int val){ addedge(from,to,val); addedge(to,from,0); } bool vis[maxn]; int dfn[maxn]; int list[maxn]; int Start=0,End; int u[5]={0,0,1,0,-1}; int w[5]={0,1,0,-1,0}; bool bfs(){ memset(vis,0,sizeof(vis)); queue<int>q; q.push(Start); vis[Start]=1; dfn[Start]=1; while(!q.empty()){ int from=q.front(); q.pop(); for(int i=head[from];i;i=edge[i].next){ int to=edge[i].to; if(edge[i].val==0||vis[to]) continue; vis[to]=1; dfn[to]=dfn[from]+1; q.push(to); } } return vis[End]; } int dfs(int x,int val){ if(val==0||x==End) return val; int flow=0; vis[x]=1; for(int &i=list[x];i;i=edge[i].next){ int to=edge[i].to; if(vis[to]||edge[i].val==0||dfn[to]!=dfn[x]+1) continue; int now=dfs(to,min(val,edge[i].val)); edge[i].val-=now; edge[count(i)].val+=now; val-=now;flow+=now; if(val<=0) break; } if(val!=flow) dfn[x]=-1; return flow; } int maxflow(){ int ans=0; while(bfs()){ memset(vis,0,sizeof(vis)); for(int i=Start;i<=End;++i) list[i]=head[i]; int now=dfs(Start,0x7fffffff); if(!now) break; ans+=now; } return ans; } int sum; int main(){ n=read(),m=read(); End=n*m+1; for(int i=1;i<=n;++i) for(int j=1;j<=m;++j){ int x=read();sum+=x; if((i+j)&1){ add(Start,calc(i,j),x); for(int k=1;k<=4;++k){ int a=i+u[k]; int b=j+w[k]; if(a==0||b==0||a>n||b>m) continue; add(calc(i,j),calc(a,b),0x7fffffff); } } else add(calc(i,j),End,x); } int ans=maxflow(); printf("%d",sum-ans); return 0; }