AC日记——pigs poj 1149

POJ - 1149

 

思路：

　　最大流；

 

代码：

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

using namespace std;

#define maxn 105
#define maxm 1005
#define maxque 200005
#define INF 0x7fffffff

int n,m,val[maxm],last[maxm],head[maxn],s,t,deep[maxn];
int E[maxque],V[maxque],F[maxque],cnt=1,ans,que[maxque];

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 int min(const int &tops_,const int &tops__)
{
    if(tops_<tops__) return tops_;
    else return tops__;
}

inline bool bfs()
{
    for(int i=s;i<=t;i++) deep[i]=-1;
    int h=0,tail=1,now;que[h]=s,deep[s]=0;
    for(;h<tail;)
    {
        now=que[h++];
        for(int i=head[now];i;i=E[i])
        {
            if(deep[V[i]]<0&&F[i])
            {
                deep[V[i]]=deep[now]+1;
                if(V[i]==t) return true;
                que[tail++]=V[i];
            }
        }
    }
    return false;
}

inline int flowing(int now,int flow)
{
    if(now==t||flow<=0) return flow;
    int oldflow=0,pos;
    for(int i=head[now];i;i=E[i])
    {
        if(deep[V[i]]==deep[now]+1&&F[i])
        {
            pos=flowing(V[i],min(flow,F[i]));
            flow-=pos,oldflow+=pos,F[i]-=pos,F[i^1]+=pos;
            if(!flow) return oldflow;
        }
    }
    if(!oldflow) deep[now]=-1;
    return oldflow;
}

int main()
{
    in(m),in(n),t=n+1;
    for(int i=1;i<=m;i++) in(val[i]);
    for(int i=1;i<=n;i++)
    {
        int pos=0,now=0,num=0;in(num);
        for(int j=1;j<=num;j++)
        {
            in(pos);
            if(!last[pos]) last[pos]=i,now+=val[pos];
            else edge_add(last[pos],i,INF),last[pos]=i;
        }
        in(pos),edge_add(i,t,pos);
        if(now) edge_add(s,i,now);
    }
    while(bfs()) ans+=flowing(s,INF);
    printf("%d\n",ans);
    return 0;
}