AC日记——[NOI2006]最大获利 bzoj 1497

1497

思路：

　　最小割；

来，上代码：

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;

#define maxn 55005
#define maxm 1005005
#define INF 0x7fffffff

int deep[maxn],que[maxm],F[maxm],cnt=;
int n,m,s,t=maxn-,head[maxn],E[maxm],V[maxm];

inline void in(int &now)
{
    char Cget=getchar();now=;
    while(Cget>''||Cget<'') Cget=getchar();
    while(Cget>=''&&Cget<='')
    {
        now=now*+Cget-'';
        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]=,head[v]=cnt;
}

inline bool bfs()
{
    memset(deep,-,sizeof(deep));
    int h=,tail=;que[]=s,deep[s]=;
    while(h<tail)
    {
        int now=que[h++];
        for(int i=head[now];i;i=E[i])
        {
            if(F[i]>&&deep[V[i]]<)
            {
                deep[V[i]]=deep[now]+;
                if(V[i]==t) return true;
                que[tail++]=V[i];
            }
        }
    }
    return false;
}

int flowing(int now,int flow)
{
    if(now==t||flow<=) return flow;
    int oldflow=;
    for(int i=head[now];i;i=E[i])
    {
        if(F[i]>&&deep[V[i]]==deep[now]+)
        {
            int pos=flowing(V[i],min(flow,F[i]));
            flow-=pos,oldflow+=pos;
            F[i]-=pos,F[i^]+=pos;
            if(flow==) return oldflow;
        }
    }
    if(oldflow==) deep[now]=-;
    return oldflow;
}

int main()
{
    in(n),in(m);int pos,u,v,sum=;
    for(int i=;i<=n;i++) in(pos),edge_add(s,i,pos);
    for(int i=;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=;while(bfs()) pos+=flowing(s,INF);
    cout<<sum-pos;
    return ;
}