poj2987 最大权闭合图

#include<stdio.h>
#include<string.h>
#include<queue>
#define INF 99999999
#define ll __int64
using namespace std;
const int maxn = 5100;
struct node
{
int to;
ll v;
int flag;
int next;
}edge[(60000+maxn)*2];
int index,pre[maxn],vis[maxn],S,T,cnt;
void add(int x,int y,int z)
{
edge[index].to=y;
edge[index].v=z;
edge[index].flag=index+1;
edge[index].next=pre[x];
pre[x]=index++;
edge[index].to=x;
edge[index].v=0;
edge[index].flag=index-1;
edge[index].next=pre[y];
pre[y]=index++;
}
ll dfs(int u,ll low)
{
int i;
ll used=0;
if(u==T)
return low;
for(i=pre[u];i!=-1&&used<low;i=edge[i].next)
{
if(edge[i].v&&vis[edge[i].to]==vis[u]+1)
{
ll a=dfs(edge[i].to,min(edge[i].v,low-used));
edge[i].v-=a;
edge[edge[i].flag].v+=a;
used+=a;
}
}
if(!used)
vis[u]=-1;
return used;
}
int BFS()
{
int i;
memset(vis,-1,sizeof(vis));
queue<int>q;
vis[0]=1;
q.push(0);
while(!q.empty())
{
int t=q.front();
q.pop();
for(i=pre[t];i!=-1;i=edge[i].next)
{
if(edge[i].v&&vis[edge[i].to]<0)
{
vis[edge[i].to]=vis[t]+1;
q.push(edge[i].to);
}
}
}
if(vis[T]>0)
return 1;
return 0;
}
void cnt_dfs(int u)
{
cnt++;
vis[u]=1;
for(int i=pre[u];i!=-1;i=edge[i].next)
{
if(!vis[edge[i].to]&&edge[i].v)
{
cnt_dfs(edge[i].to);
}
}
}
int main()
{
int n,m,i;
while(~scanf("%d%d",&n,&m))
{
cnt=0;
ll sum=0;
index=1;
memset(pre,-1,sizeof(pre));
for(i=1;i<=n;i++)
{
ll x;
scanf("%I64d",&x);
if(x>0)
{
sum+=x;
add(0,i,x);
}
else add(i,n+1,-x);
}
for(i=0;i<m;i++)
{
int x,y;
scanf("%d%d",&x,&y);
add(x,y,INF);
}
ll ans=0;
S=0,T=n+1;
while(BFS())
{
　　　　　　while(1){
ll a=dfs(0,INF);
if(!a)break;
ans+=a;
　　　　   }
}
memset(vis,0,sizeof(vis));
cnt_dfs(0);
printf("%d %I64d\n",cnt-1,sum-ans);
}
}