bzoj2039: [2009国家集训队]employ人员雇佣

传送门：http://www.lydsy.com/JudgeOnline/problem.php?id=2039

思路：还是二元组建图

先求出总收益，再解方程建图求最小割

题意有些坑

c+d=w[i]+w[j]

a+b=2*E[i][j]

a+d+f=A[j]+3*E[i][j]

b+c+e=A[i]+3*E[i][j]

然后就没有然后了

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
typedef long long ll;
const int maxn=1050,maxm=2000010;
const ll inf=1ll<<50;
using namespace std;
int n;
ll sum,E[maxn][maxn],A[maxn],B[maxn],cost[maxn];

struct Flow{
	int pre[maxm],now[maxn],son[maxm],tot,dis[maxn],q[maxm+10],head,tail,S,T;ll val[maxm];
	void add(int a,int b,ll c){pre[++tot]=now[a],now[a]=tot,son[tot]=b,val[tot]=c;}
	void ins(int a,int b,ll c){add(a,b,c),add(b,a,0);}
	void ins2(int a,int b,ll c){add(a,b,c),add(b,a,c);}
	void init(){memset(now,0,sizeof(now)),tot=1,S=maxn-1,T=maxn-2;}
	void build(){
		for (int i=1;i<=n;i++)
			for (int j=i+1;j<=n;j++)
				A[i]+=E[i][j],A[j]+=E[i][j],ins2(i,j,2ll*E[i][j]);
		for (int i=1;i<=n;i++) ins(i,T,cost[i]);
		for (int i=1;i<=n;i++) ins(S,i,A[i]);
	}
	bool bfs(){
		memset(dis,-1,sizeof(dis));
		q[tail=1]=S,dis[S]=head=0;
		while (head!=tail){
			if (++head>maxn) head=1;
			int x=q[head];
			for (int y=now[x];y;y=pre[y])
				if (val[y]&&dis[son[y]]==-1){
					if (++tail>maxn) tail=1;
					dis[son[y]]=dis[x]+1,q[tail]=son[y];
				}
		}
		return dis[T]>0;
	}
	ll find(int x,ll low){
		if (x==T) return low;
		int y;ll res=0;
		for (y=now[x];y;y=pre[y]){
			if (dis[son[y]]!=dis[x]+1||!val[y]) continue;
			ll tmp=find(son[y],min(val[y],low));
			res+=tmp,low-=tmp,val[y]-=tmp,val[y^1]+=tmp;
			if (!low) break;
		}
		if (!y) dis[x]=-1;
		return res;
	}
	void work(){
		ll res=0;
		while (bfs()) res+=find(S,inf);
		printf("%lld\n",sum-res);
	}
}F;

int main(){
	scanf("%d",&n),F.init();
	for (int i=1;i<=n;i++) scanf("%lld",&cost[i]);
	for (int i=1;i<=n;i++) for (int j=1;j<=n;j++) scanf("%lld",&E[i][j]),sum+=E[i][j];
	F.build(),F.work();
	return 0;
}