BZOJ 1497--最大获利(最小割)

#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<iostream>
#define inf 1000000000
#define N 100050
using namespace std;
inline int Read(){
    int x=0,f=1;char ch=getchar();
    while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
    while(ch>=‘0‘&&ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}
    return x*f;
}
char ch;
int n,m,d,S,T,ans,tot;
int cnt=1;
int hed[N],h[N],q[N];
struct edge{
    int r,nxt,v;
}e[500000];
void insert(int u,int v,int w){
    e[++cnt].r=v;e[cnt].nxt=hed[u];hed[u]=cnt;e[cnt].v=w;
    e[++cnt].r=u;e[cnt].nxt=hed[v];hed[v]=cnt;e[cnt].v=0;
}
bool bfs(){
    int head=0,tail=1,now;
    memset(h,-1,sizeof(h));
    h[S]=1;q[1]=S;
    while(head!=tail){
        head++;now=q[head];
        for(int i=hed[now];i;i=e[i].nxt)
            if(e[i].v&&h[e[i].r]==-1){
                h[e[i].r]=h[now]+1;
                q[++tail]=e[i].r;
            }
    }
    return h[T]!=-1;
}
int dfs(int x,int F){
    if(x==T) return F;
    int w,used=0;
    for(int i=hed[x];i;i=e[i].nxt)
        if(h[x]+1==h[e[i].r]){
            w=F-used;
            w=dfs(e[i].r,min(w,e[i].v));
            e[i].v-=w;
            e[i^1].v+=w;
            used+=w;
            if(used==F) return F;
        }
    if(!used) h[x]=-1;
    return used;
}
void dinic(){
    while( bfs() )
        ans+=dfs(0,inf);
}
int main(){
	int sum=0;
	int u,v,w;
    n=Read();m=Read();
    S=0;T=n+m+1;
    for(int i=1;i<=n;i++){
    	w=Read();
    	insert(S,i,w);
	}
	for(int i=1;i<=m;i++){
		u=Read();v=Read();w=Read();
		insert(u,i+n,inf);
		insert(v,i+n,inf);
		insert(i+n,T,w);
		sum+=w;
	}
    dinic();
    printf("%d\n",sum-ans);
    return 0;
}