思路：

　　最小割；

 

来，上代码：

#include 
     
      #include 
      
       #include 
       
        #include 
        
         using namespace std;#define maxn 55005#define maxm 1005005#define INF 0x7fffffffint deep[maxn],que[maxm],F[maxm],cnt=1;int n,m,s,t=maxn-1,head[maxn],E[maxm],V[maxm];inline void in(int &now){    char Cget=getchar();now=0;    while(Cget>'9'||Cget<'0') Cget=getchar();    while(Cget>='0'&&Cget<='9')    {        now=now*10+Cget-'0';        Cget=getchar();    }}inline void edge_add(int u,int v,int f){    E[++cnt]=head[u],V[cnt]=v,F[cnt]=f,head[u]=cnt;    E[++cnt]=head[v],V[cnt]=u,F[cnt]=0,head[v]=cnt;}inline bool bfs(){    memset(deep,-1,sizeof(deep));    int h=0,tail=1;que[0]=s,deep[s]=0;    while(h
         
          0&&deep[V[i]]<0)            {                deep[V[i]]=deep[now]+1;                if(V[i]==t) return true;                que[tail++]=V[i];            }        }    }    return false;}int flowing(int now,int flow){    if(now==t||flow<=0) return flow;    int oldflow=0;    for(int i=head[now];i;i=E[i])    {        if(F[i]>0&&deep[V[i]]==deep[now]+1)        {            int pos=flowing(V[i],min(flow,F[i]));            flow-=pos,oldflow+=pos;            F[i]-=pos,F[i^1]+=pos;            if(flow==0) return oldflow;        }    }    if(oldflow==0) deep[now]=-1;    return oldflow;}int main(){    in(n),in(m);int pos,u,v,sum=0;    for(int i=1;i<=n;i++) in(pos),edge_add(s,i,pos);    for(int i=1;i<=m;i++)    {        in(u),in(v),in(pos);        sum+=pos;        edge_add(u,i+n,INF);        edge_add(v,i+n,INF);        edge_add(i+n,t,pos);    }    pos=0;while(bfs()) pos+=flowing(s,INF);    cout<