BZOJ1565: [NOI2009]植物大战僵尸

题目：http://www.lydsy.com/JudgeOnline/problem.php?id=1565

可以发现点(i,j+1)保护点(i,j)，然后加上题目给的保护关系连边。拓扑排序搞出所有合法的方案，然后就是最大权闭合子图辣。

#include<cstring>
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<queue>
#define rep(i,l,r) for (int i=l;i<=r;i++)
#define down(i,l,r) for (int i=l;i>=r;i--)
#define clr(x,y) memset(x,y,sizeof(x))
#define maxn 600500
#define ll long long
#define inf int(1e9)
using namespace std;
struct data{int obj,pre,c;
}e[maxn*2],ed[maxn*2];
int head[maxn],d[maxn],head2[maxn],a[maxn],del[maxn],uu[maxn],q[maxn];
int tot,tot2=1,n,m,t,top,ans;
void insert(int x,int y,ll z){
    e[++tot].obj=y; e[tot].pre=head[x]; head[x]=tot; e[tot].c=z;
}
void insert2(int x,int y,int z){
    ed[++tot2].obj=y; ed[tot2].pre=head2[x]; head2[x]=tot2; ed[tot2].c=z;
    ed[++tot2].obj=x; ed[tot2].pre=head2[y]; head2[y]=tot2; ed[tot2].c=0;
}
int p(int x,int y){
    return (x-1)*m+y;
}
int read(){
    int x=0,f=1; char ch=getchar();
    while (!isdigit(ch)){if (ch=='-') f=-1; ch=getchar();}
    while (isdigit(ch)){x=x*10+ch-'0'; ch=getchar();}
    return x*f;
}
void insert(int x,int y){
    d[y]++;
    e[++tot].obj=y; e[tot].pre=head[x]; head[x]=tot; 
}
void dfs(int u){
    del[u]=1;
    for (int j=head[u];j;j=e[j].pre){
        int v=e[j].obj; 
        if (!del[v]) dfs(v);
    }
}
bool bfs(){
    queue<int> q; q.push(0); clr(uu,-1); uu[0]=0;
    while (!q.empty()){
        int u=q.front(); q.pop();
        for (int j=head2[u];j;j=ed[j].pre){
            int v=ed[j].obj;
            if (ed[j].c>0&&uu[v]==-1){
                uu[v]=uu[u]+1; q.push(v);
            }
        }
    }
    if (uu[t]==-1) return 0;
    return 1;
}
int dfs(int x,int mx){
    if (x==t||mx==0) return mx;
    int used=0;
    for (int j=head2[x];j;j=ed[j].pre){
        int v=ed[j].obj;
        if (uu[v]==uu[x]+1&&ed[j].c>0){
            int w=dfs(v,min(ed[j].c,mx-used));
            if (w<=0) {uu[v]=-1; continue;}
            ed[j].c-=w; ed[j^1].c+=w; used+=w;
            if (used==mx) return used;
        }
    }
    return used;
}
int dinic(){
    int ans=0;
    while (bfs()){
        ans+=dfs(0,inf);
    }
    return ans;
}
int main(){
    n=read(); m=read();
    rep(i,1,n) rep(j,1,m) {
        a[p(i,j)]=read();
        int s=read();
        rep(k,1,s){
            int x=read(),y=read(); x++; y++;
            insert(p(i,j),p(x,y));
        }
    }
    rep(i,1,n) down(j,m,2) insert(p(i,j),p(i,j-1));
    rep(i,1,n) rep(j,1,m) if (!d[p(i,j)]) q[++top]=p(i,j); else del[p(i,j)]=1;
    while (top){
        int u=q[top--];
        for (int j=head[u];j;j=e[j].pre){
            int v=e[j].obj;
            d[v]--;
            if (!d[v]) q[++top]=v,del[v]=0;
        }
    }
    rep(i,1,n*m) if (del[i]) dfs(i);
    t=n*m+1;
    rep(i,1,n*m) if (!del[i]){ 
        if (a[i]>=0) insert2(i,t,a[i]),ans+=a[i];
        else insert2(0,i,-a[i]);
        for (int j=head[i];j;j=e[j].pre){
            int v=e[j].obj;
            if (!del[v]) insert2(i,v,inf);
        }
    }
    printf("%d
",ans-dinic());
    return 0;
}