noi2006day2_最大获利 网络流

这道题是上一题的数据加强版，dinic表示毫无压力；

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cstdlib>
#include<ctime>
#include<algorithm>
using namespace std;
const int maxn=55010;
const int inf=1000000000;
const int s=0,t=55001;
struct node{
    int y,next,flow,re;
}e[maxn*10];
int linkk[maxn*3],len=0,n,m,w[maxn],sum=0;
void print(int x){printf("%d
",x);}
void print(int x,int y){printf("%d %d
",x,y);}
void insert(int x,int y,int flow){
    e[++len].y=y;e[len].flow=flow;
    e[len].next=linkk[x];linkk[x]=len;e[len].re=len+1;
    e[++len].y=x;e[len].flow=0;
    e[len].next=linkk[y];linkk[y]=len;e[len].re=len-1;
}
void init(){
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++)scanf("%d",&w[i]);
    int x,y,v;
    for(int i=1;i<=m;i++){
        scanf("%d%d%d",&x,&y,&v);sum+=v;
        insert(s,i,v);insert(i,m+x,inf);insert(i,m+y,inf);
    }
    for(int i=1;i<=n;i++)insert(m+i,t,w[i]);
}
int q[maxn],tail=0,level[maxn],head=0;
bool bfs(){
    memset(level,-1,sizeof(level));
    head=0;tail=0;level[s]=1;q[++tail]=s;
    while(++head<=tail){
        int x=q[head];
        for(int i=linkk[x];i;i=e[i].next){
            if(level[e[i].y]==-1&&e[i].flow){
                q[++tail]=e[i].y;
                level[e[i].y]=level[x]+1;
            }
        }
    }
    return level[t]>0;
}
int find(int x,int flow){
    if(x==t)return flow;
    int maxflow=0,d=0;
    for(int i=linkk[x];i&&maxflow<flow;i=e[i].next){
        if(level[e[i].y]==level[x]+1&&e[i].flow){
            if(d=find(e[i].y,min(flow-maxflow,e[i].flow))){
                maxflow+=d;
                e[i].flow-=d;
                e[e[i].re].flow+=d;
            }
        }
    }
    if(!maxflow)level[x]=-1;
    return maxflow;
}
void work(){
    int d=0,ans=0;
    while(bfs())
        while(d=find(s,inf))
            ans+=d;
    cout<<sum-ans<<endl;
}
int main(){
    freopen("1.in","r",stdin);
    freopen("1.out","w",stdout);
    init();
    work();
}