NOI2009 植物大战僵尸

Posted 2020-09-29

啊一道好题
感觉写得挺爽的啊这题
这种有一点懵逼然后学了一点东西之后很明朗的感觉真是好！
预处理参考 ：http://www.cppblog.com/MatoNo1/archive/2014/11/01/142798.html?opt=admin
建图参考 ：http://hihocoder.com/problemset/problem/1398?sid=1010444

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<string>
#include<algorithm>
#include<queue>
#include<vector>
#define N 80000
#define mod
#define inf 300000000
#define rg register
using namespace std;
typedef long long ll;
int n,m,tot=0,cnt=0,tmp=0,s,t;
int dis[N],hd[N],head[N],c[N],in[N],d[(N<<3)],w[N];
bool del[N];
struct hh{
	int to,nxt,w;
}b1[N*100],b[N*100];
int p (int x,int y) { return (x-1)*m+y; }
void link(int x,int y,int w){
	b1[tot].nxt=hd[x];
	b1[tot].to=y;
	b1[tot].w=w;
	hd[x]=tot++;
}
void lnk(int x,int y,int w){
	b[tot].nxt=head[x];
	b[tot].to=y;
	b[tot].w=w;
	head[x]=tot++;
}
void dele(int x){
	del[x]=1;
	for (int i=hd[x];i!=-1;i=b1[i].nxt)
		if (!del[b1[i].to]) dele(b1[i].to);
}
void top(){
	int h=0,t=0;
	for (int i=1;i<=cnt;++i){
		if (!in[i]) d[++t]=i;
		else del[i]=1;
	}
	while (h<=t){
		int x=d[++h];
		for (int i=hd[x];i!=-1;i=b1[i].nxt){
			in[b1[i].to]--,del[b1[i].to]=0;
			if (!in[b1[i].to]) d[++t]=b1[i].to;
		}
	}
	for (int i=1;i<=cnt;++i) if (del[i]) dele(i);
}
bool bfs(){
	queue <int> q;
	memset(dis,-1,sizeof(dis));
	q.push(s);dis[s]=0;
	while (!q.empty()){
		int h=q.front();
		q.pop();
		for (int i=head[h];i!=-1;i=b[i].nxt){
			int v=b[i].to;
			if (dis[v]!=-1||b[i].w<=0) continue;
			dis[v]=dis[h]+1;
			if (v==t) return 1;
			q.push(v);
		}
	}
	return dis[t]==-1?0:1;
}
int dfs(int u,int f){
	if (u==t||!f) return f;
	int res=f;
	for (int &i=c[u];i!=-1;i=b[i].nxt){
		int v=b[i].to;
		if (dis[v]!=dis[u]+1||b[i].w<=0) continue;
		int d=dfs(v,min(res,b[i].w));
		b[i].w-=d,b[i^1].w+=d;
		res-=d;
		if (res<=0) break;
	}
	return f-res;
}
int dinic(){
	int ans=0;
	while (bfs()){
		for (int i=s;i<=t;++i) c[i]=head[i];
		ans+=dfs(s,inf);
	}
	return ans;
}
int main(){
	freopen ("pvz.in","r",stdin);
	freopen ("pvz.out","w",stdout);
	memset(hd,-1,sizeof(hd));
	memset(head,-1,sizeof(head));
	scanf ("%d%d",&n,&m);
	int x,y,z;
	for (int i=1;i<=n;++i)
		for (int j=1;j<=m;++j){
			scanf ("%d%d",&w[p(i,j)],&z);
			for (int k=1;k<=z;++k) scanf ("%d%d",&x,&y),link(p(i,j),p(x+1,y+1),0),in[p(x+1,y+1)]++;
		}
	for (int i=1;i<=n;++i)
		for (int j=2;j<=m;++j) link(p(i,j),p(i,j-1),0),in[p(i,j-1)]++;
	cnt=n*m;
	top();
	s=0,t=cnt+1,tmp=0;
	tot=0;
	for (int i=1;i<=cnt;++i){
		if (del[i]) continue;
		if (w[i]>0) tmp+=w[i],lnk(i,t,w[i]),lnk(t,i,0);
		else lnk(s,i,-w[i]),lnk(i,s,0);
		for (int j=hd[i];j!=-1;j=b1[j].nxt)
			if (!del[b1[j].to]) lnk(i,b1[j].to,inf),lnk(b1[j].to,i,0);
	}
	tmp-=dinic();
	printf ("%d\n",max(0,tmp));
	return 0;
}