P4474 王者之剑

#include<bits/stdc++.h>
using namespace std;
#define mp make_pair
#define fi first
#define se second
#define lson now<<1
#define rson now<<1|1
typedef long long ll;
const int maxn=205;
const int maxm=40005;
int id[maxn][maxn],cnt;
int val[maxn][maxn],n,m;
int S,T;
int dx[4]={0,1,0,-1};
int dy[4]={1,0,-1,0};
const ll inf=1e17;
int head[10005],tot=1,cur[10005];
struct edge
{
    int to,nxt;
    ll v;
}e[maxm<<1];
void add(int x,int y,ll z)
{
    e[++tot].to=y; e[tot].nxt=head[x]; e[tot].v=z; head[x]=tot;
    e[++tot].to=x; e[tot].nxt=head[y]; e[tot].v=0; head[y]=tot;
}
int dep[10005];
bool bfs()
{
    for(int i=S;i<=T;i++)
        dep[i]=-1,cur[i]=head[i];
    // memset(dep,-1,sizeof(dep));
    // memcpy(cur,head,sizeof(cur));
    queue <int> q;
    dep[S]=0;
    q.push(S);
    while(!q.empty())
    {
        int u=q.front(); q.pop();
        for(int i=head[u];i;i=e[i].nxt)
        {
            int to=e[i].to;
            if(dep[to]!=-1 || !e[i].v) continue;
            q.push(to);
            dep[to]=dep[u]+1;
        }
    }
    return (dep[T]!=-1);
}
ll dfs(int u,ll flow)
{
    if(u==T) return flow;
    ll res=0;
    for(int &i=cur[u];i;i=e[i].nxt)
    {
        int to=e[i].to;
        if(dep[to]!=dep[u]+1 || e[i].v<=0) continue;
        ll tmp=dfs(to,min(e[i].v,flow));
        flow-=tmp; res+=tmp;
        e[i].v-=tmp; e[i^1].v+=tmp;
        if(!flow) break;
    }
    if(!res) dep[u]=-1;
    return res;
}
ll ans;
ll dinic()
{
    ll ans=0;
    while(bfs())
    {
        ans+=dfs(S,inf);
    }
    return ans;
}
int main()
{
    // freopen("a.in","r",stdin);
    // freopen("a.out","w",stdout);
    scanf("%d%d",&n,&m);
    S=0; T=n*m+1;
    ll sum=0;
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
        {
            scanf("%d",&val[i][j]);
            id[i][j]=++cnt;
            sum+=val[i][j];
        }
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
        {
            if((i+j)%2==0)
            {
                add(S,id[i][j],val[i][j]);
                for(int k=0;k<4;k++)
                {
                    int tox=i+dx[k];
                    int toy=j+dy[k];
                    if(tox<1 || toy<1 || tox>n || toy>m) continue;
                    add(id[i][j],id[tox][toy],inf/2);
                }
            }
            else add(id[i][j],T,val[i][j]);
        }

    printf("%lld",sum-dinic());
    return 0;
}