P4474 王者之剑

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<string>
#include<queue>
using namespace std;
typedef long long LL;
const LL maxn=500000;
const LL inf=0x3f3f3f3f;
const LL dx[5]={0,-1,0,1,0};
const LL dy[5]={0,0,1,0,-1};
inline LL read(){
	LL x=0,f=1; char c=getchar();
	while(c<‘0‘||c>‘9‘){
		if(c==‘-‘) f=-1; c=getchar();
	}
	while(c>=‘0‘&&c<=‘9‘){
		x=x*10+c-‘0‘; c=getchar();
	}return x*f;
}
struct node{
	LL to,next,flow;
}dis[maxn];
LL num=-1,s,t,n,m,ans;
LL head[maxn],dep[maxn];
inline void Add(LL u,LL v,LL flow){
	dis[++num]=(node){v,head[u],flow}; head[u]=num;
}
inline bool Bfs(){
	memset(dep,0,sizeof(dep));
	queue<LL> que;
	que.push(s);
	dep[s]=1;
	while(que.size()){
		LL u=que.front();
		que.pop();
		for(LL i=head[u];i!=-1;i=dis[i].next){
			LL v=dis[i].to;
			if(!dep[v]&&dis[i].flow){
				dep[v]=dep[u]+1;
				que.push(v);
			}
		}
	}
	return dep[t];
}
LL Dfs(LL u,LL flow){
	if(u==t)
	    return flow;
	LL tmp=flow;
	for(LL i=head[u];i!=-1;i=dis[i].next){
		LL v=dis[i].to;
		if(dep[v]==dep[u]+1&&dis[i].flow&&tmp){
			LL now=Dfs(v,min(tmp,dis[i].flow));
			if(now){
				dis[i].flow-=now;
				dis[i^1].flow+=now;
				tmp-=now;
			}else
			    dep[v]=inf;
		}
	}
	return flow-tmp;
}
inline LL Dinic(){
	LL sum=0;
	while(Bfs())
		sum+=Dfs(s,inf);
	return sum;
}
int main(){
	n=read(); m=read();
	s=0; t=n*m+1;
	memset(head,-1,sizeof(head));
	for(LL i=1;i<=n;++i)
	    for(LL j=1;j<=m;++j){
	    	LL val=read();
	    	ans+=val;
	    	if((i+j)&1){
	    		Add(s,(i-1)*m+j,val);
	    		Add((i-1)*m+j,s,0); 
			}else{
		        Add((i-1)*m+j,t,val);
		        Add(t,(i-1)*m+j,0);
			}
		}
	
	    
	for(LL i=1;i<=n;++i)
	    for(LL j=1;j<=m;++j){
	    	if((i+j)&1){
	    		for(LL k=1;k<=4;++k){
	    			LL nx=i+dx[k],ny=j+dy[k];
	    			if(nx<1||nx>n||ny<1||ny>m)
	    			    continue;
	    			Add((i-1)*m+j,(nx-1)*m+ny,inf);
	    			Add((nx-1)*m+ny,(i-1)*m+j,0);
				}
			}
		}
	ans-=Dinic();
	printf("%lld",ans);
	return 0;
}