AC日记——Destroying The Graph poj 2125

#include <queue>
#include <cstdio>
#include <cstring>
#include <iostream>

#define INF 0x7ffffff

using namespace std;

struct EdgeType {
    int v,e,f;
};
struct EdgeType edge[5000<<5];

int n,m,vout[105],vin[105],s,t;
int head[505],deep[505],cnt=1,ans;

bool if_[505];

char Cget;

inline void in(int &now)
{
    now=0,Cget=getchar();
    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)
{
    edge[++cnt].v=v,edge[cnt].f=f,edge[cnt].e=head[u],head[u]=cnt;
    edge[++cnt].v=u,edge[cnt].f=0,edge[cnt].e=head[v],head[v]=cnt;
}

bool BFS()
{
    for(int i=s;i<=t;i++) deep[i]=-1;
    queue<int>que;que.push(s);deep[s]=0;
    while(!que.empty())
    {
        int now=que.front();
        for(int i=head[now];i;i=edge[i].e)
        {
            if(deep[edge[i].v]<0&&edge[i].f>0)
            {
                deep[edge[i].v]=deep[now]+1;
                if(edge[i].v==t) return true;
                que.push(edge[i].v);
            }
        }
        que.pop();
    }
    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=edge[i].e)
    {
        if(deep[edge[i].v]!=deep[now]+1||edge[i].f==0) continue;
        int pos=flowing(edge[i].v,min(flow,edge[i].f));
        flow-=pos;
        oldflow+=pos;
        edge[i].f-=pos;
        edge[i^1].f+=pos;
        if(flow==0) return oldflow;
    }
    if(oldflow==0) deep[now]=-1;
    return oldflow;
}

void check(int now)
{
    if_[now]=true;
    for(int i=head[now];i;i=edge[i].e)
    {
        if(!edge[i].f||if_[edge[i].v]) continue;
        check(edge[i].v);
    }
}

int main()
{
    in(n),in(m);
    s=0,t=n+n+1;
    for(int i=1;i<=n;i++)
    {
        in(vout[i]);
        edge_add(i+n,t,vout[i]);
    }
    for(int i=1;i<=n;i++)
    {
        in(vin[i]);
        edge_add(s,i,vin[i]);
    }
    int u,v;
    for(int i=1;i<=m;i++)
    {
        in(u),in(v);
        edge_add(u,v+n,INF);
    }
    while(BFS()) ans+=flowing(s,INF);
    cout<<ans;ans=0;
    putchar(‘\n‘);check(s);
    for(int i=1;i<=n;i++)
    {
        if(!if_[i]) ans++;
        if(if_[i+n]) ans++;
    }
    cout<<ans;putchar(‘\n‘);
    for(int i=1;i<=n;i++)
    {
        if(!if_[i]) printf("%d -\n",i);
        if(if_[i+n]) printf("%d +\n",i);
    }
    return 0;
}