POJ 1966 求无向图点连通度

思路：

n^2枚举（必须要n^2枚举啊）+拆点

特此嘲讽网上诸多垃圾题解，你们许多都是错的 —yyh

//By SiriusRen

#include <queue>

#include <cstdio>

#include <cstring>

#include <algorithm>

using namespace std;

#define N 5555

int n,m,xx,yy,inf=0x3fffff,ans,ed=105;

struct Node{int x,y;}point[N];

struct Dinic{

    int first[107],next[N],v[N],w[N],tot,vis[107];

    void solve(int x,int y){

        memset(first,-1,sizeof(first)),tot=0;

        add(0,x,inf),add(x,x+n,inf),add(y,y+n,inf),add(y+n,105,inf);

        for(int i=1;i<=n;i++)add(i,i+n,1);

        for(int i=1;i<=m;i++)add(point[i].x+n,point[i].y,inf),add(point[i].y+n,point[i].x,inf);

        ans=min(ans,x=flow());

    }

    void add(int x,int y,int z){Add(x,y,z),Add(y,x,0);}

    void Add(int x,int y,int z){w[tot]=z,v[tot]=y,next[tot]=first[x],first[x]=tot++;}

    bool tell(){

        memset(vis,-1,sizeof(vis)),vis[0]=0;

        queue<int>q;q.push(0);

        while(!q.empty()){

            int t=q.front();q.pop();

            for(int i=first[t];~i;i=next[i])

                if(vis[v[i]]==-1&&w[i])

                    vis[v[i]]=vis[t]+1,q.push(v[i]);

        }

        return vis[ed]!=-1;

    }

    int zeng(int x,int y){

        if(x==ed)return y;

        int r=0;

        for(int i=first[x];~i&&y>r;i=next[i])

            if(vis[v[i]]==vis[x]+1&&w[i]){

                int t=zeng(v[i],min(y-r,w[i]));

                w[i]-=t,w[i^1]+=t,r+=t;

            }

        if(!r)vis[x]=-1;

        return r;

    }

    int flow(){

        int jy=0,tmp;

        while(tell())while(tmp=zeng(0,inf))jy+=tmp;

        return jy;

    }

}dinic;

int main(){

    while(~scanf("%d%d",&n,&m)){

        ans=inf;

        for(int i=1;i<=m;i++){

            scanf(" (%d,%d)",&point[i].x,&point[i].y);

            point[i].x++,point[i].y++;

        }

        for(int i=1;i<=n;i++)

            for(int j=1;j<=n;j++)

                if(i!=j)dinic.solve(i,j);

        if(ans==inf)printf("%d\n",n);

        else printf("%d\n",ans);

    }

}