bzoj 2744: [HEOI2012]朋友圈 二分图匹配

#include<iostream>
#include<cstring>
#include<algorithm>
#include<cstdio>
#include<vector>
using namespace std;
#define MAXN 3100
#define MAXV MAXN
#define MAXE 11000000
struct Edge
{
        int np;
        Edge *next;
}E[MAXE],*V[MAXV];
int tope=-1;
void addedge(int x,int y)
{
        E[++tope].np=y;
        E[tope].next=V[x];
        V[x]=&E[tope];
}
vector<int> blst[MAXN];
int a[MAXN],b[MAXN];
int vis[MAXN],vistime;
int ptr[MAXN];
bool find(int now)
{
        if (vis[now]==vistime)return false;
        vis[now]=vistime;
        Edge *ne;
        for (ne=V[now];ne;ne=ne->next)
        {
                if (ptr[ne->np]==-1 || find(ptr[ne->np]))
                {
                        ptr[ne->np]=now;
                        return true;
                }
        }
        return false;
}
int work(vector<int> seq)
{
        for (int i=0;i<seq.size();i++)ptr[seq[i]]=-1;
        for (int i=0;i<seq.size();i++)
        {
                for (int j=i+1;j<seq.size();j++)
                {
                        if (((b[seq[i]]^b[seq[j]])&1) && !__builtin_parity(b[seq[i]]|b[seq[j]]))
                        {
                                addedge(seq[i],seq[j]);
                                addedge(seq[j],seq[i]);
                        }
                }
        }
        int ret=0;
        for (int i=0;i<seq.size();i++)
        {
                if ((b[seq[i]]&1))
                {
                        ++vistime;
                        ret+=find(seq[i]);
                }
        }
        ret=seq.size()-ret;
        for (int i=0;i<seq.size();i++)V[seq[i]]=0;tope=-1;
        return ret;
}

int ans=0;
int main()
{
        freopen("input.txt","r",stdin);
        freopen("output.txt","w",stdout);
        int n,m,q;
        int x,y;
        vector<int> seq;
        scanf("%d%d",&n,&m);
        scanf("%d",&q);
        for (int i=1;i<=n;i++)
                scanf("%d",a+i);
        for (int i=1;i<=m;i++)
                scanf("%d",b+i);
        for (int i=1;i<=n;i++)blst[i].clear();
        for (int i=1;i<=q;i++)
        {
                scanf("%d%d",&x,&y);
                blst[x].push_back(y);
        }
        for (int i=1;i<=n;i++)
        {
                sort(blst[i].begin(),blst[i].end());
                blst[i].erase(unique(blst[i].begin(),blst[i].end()),blst[i].end());
        }
        //Nothing In A
        for (int i=1;i<=m;i++)seq.push_back(i);
        ans=max(ans,work(seq));
        seq.clear();
        for (int i=1;i<=n;i++)
        {
                for (int j=0;j<blst[i].size();j++)
                        seq.push_back(blst[i][j]);
                if (seq.size()+1>ans)
                        ans=max(ans,work(seq)+1);
                seq.clear();
        }
        for (int i=1;i<=n;i++)
        {
                for (int j=i+1;j<=n;j++)
                {
                        if (!((a[i]^a[j])&1))continue;
                        vector<int> :: iterator it1,it2;
                        it1=blst[i].begin();
                        it2=blst[j].begin();
                        while (it1!=blst[i].end() && it2!=blst[j].end())
                        {
                                if (*it1==*it2)
                                {
                                        seq.push_back(*it1);
                                        it1++,it2++;
                                }else if (*it1<*it2)
                                {
                                        it1++;
                                }else
                                {
                                        it2++;
                                }
                        }
                        if (seq.size()+2>ans)
                                ans=max(ans,work(seq)+2);
                        seq.clear();
                }
        }
        printf("%d\n",ans);
}