bzoj1497: [NOI2006]最大获利

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<queue>
#define inf 0x7f7f7f7f
using namespace std;
queue<int> q;
int read()
{
char ch=getchar();int f=0;
while(ch<'0'||ch>'9') ch=getchar();
while(ch>='0'&&ch<='9')
{f=(f<<1)+(f<<3)+ch-'0';
ch=getchar();}
return f;
}
int n,m,head[60005],tot,sum,ans,dis[60005];
struct node
{
int from;
int to;
int next;
int w;
}edge[400005];
int s,t;
bool bfs()
{
memset(dis,0,sizeof(dis));
dis[s]=1;
q.push(s);
while(!q.empty())
{
int x=q.front();
q.pop();
for(int i=head[x];i!=-1;i=edge[i].next)
{
if(!dis[edge[i].to]&&edge[i].w)
{
dis[edge[i].to]=dis[x]+1;
q.push(edge[i].to);
}
}
}
if(dis[t])
return 1;
return 0;
}
int dfs(int x,int flow)
{
if(x==t||!flow)
return flow;
int ret=0;
for(int i=head[x];i!=-1;i=edge[i].next)
{
if(dis[edge[i].to]==dis[x]+1)
{
int f=dfs(edge[i].to,min(flow,edge[i].w));
edge[i].w-=f;edge[i^1].w+=f;
ret+=f;flow-=f;
if(!flow)
break;
}
}
if(!ret)
dis[x]=-1;
return ret;
}
void dinic()
{
while(bfs())
{
ans+=dfs(s,0x7f7f7f7f);
}
}
void add(int u,int v,int w)
{
edge[tot].from=u;
edge[tot].to=v;
edge[tot].w=w;
edge[tot].next=head[u];
head[u]=tot++;
}
int main()
{
memset(head,-1,sizeof(head));
n=read(),m=read();
s=0,t=m+n+1;
for(int i=1;i<=n;i++)
{
int x=read();
add(s,i,x);
add(i,s,0);
}
for(int i=1;i<=m;i++)
{
int x=read(),y=read(),z=read();
add(i+n,t,z);
add(t,i+n,0);
add(x,i+n,inf);
add(i+n,x,0);
add(y,i+n,inf);
add(i+n,y,0);
sum+=z;
}
dinic();
printf("%d",sum-ans);
}