poj 2289 Jamie's Contact Groups 二分图多重匹配

来源：互联网发布：c语言贪吃蛇编辑：程序博客网时间：2024/04/29 13:19
#include<stdio.h>#include<string.h>#include<queue>#include<vector>using namespace std;const int N=2048;const int inf=1<<24;struct Edge{    int from,to,cap,flow;};vector<Edge>edges;vector<int>G[N];int s,t,a[500*N],b[500*N];int vis[N];int d[N];int cur[N];void AddEdge(int from,int to,int cap){    Edge tp;    tp.from=from,tp.to=to,tp.cap=cap,tp.flow=0;    edges.push_back(tp);    tp.from=to,tp.to=from,tp.cap=0,tp.flow=0;    edges.push_back(tp);    int g_size=edges.size();    G[from].push_back(g_size-2);    G[to].push_back(g_size-1);}bool BFS(){    memset(vis,0,sizeof(vis));    queue<int>Q;    Q.push(s);    d[s]=0;    vis[s]=1;    while(!Q.empty())    {        int x=Q.front();        Q.pop();        for(int i=0; i<G[x].size(); i++)        {            Edge &e=edges[G[x][i]];            if(!vis[e.to]&&e.cap>e.flow)            {                vis[e.to]=1;                d[e.to]=d[x]+1;                Q.push(e.to);            }        }    }    return vis[t];}int DFS(int x,int a){    if(x==t||a==0) return a;    int flow=0,f;    for(int &i=cur[x]; i<G[x].size(); i++)    {        Edge &e=edges[G[x][i]];        if(d[x]+1==d[e.to]&&(f=DFS(e.to,min(a,e.cap-e.flow)))>0)        {            e.flow+=f;            edges[G[x][i]^1].flow-=f;            flow+=f;            a-=f;            if(a==0) break;        }    }     if(!flow) d[x] = -1;    return flow;}int Maxflow(int st,int ed){    int flow=0;    while(BFS())    {        memset(cur,0,sizeof(cur));        flow+=DFS(st,inf);    }    return flow;}int main(){    int n,m,u,v,c,l,r,ct,mid;    char st[1024],ch;    while(~scanf("%d%d",&n,&m))    {        if(n==0&&m==0) break;        s=0;        t=n+m+1;        ct=0;         for(int i=1;i<=n;i++)        {            scanf("%s",st);            ch=getchar();            while(ch==' ')            {                scanf("%d",&u);                a[ct]=i;                b[ct++]=u+n+1;                //printf("%d\n",ct);                ch=getchar();            }        }        l=0,r=n;        while(l<r)        {            mid=(l+r)/2;            edges.clear();            for(int i=0; i<N; i++) G[i].clear();            for(int i=1;i<=n;i++)                AddEdge(s,i,1);            for(int i=n+1;i<=n+m;i++)                AddEdge(i,t,mid);            for(int i=0;i<ct;i++)                AddEdge(a[i],b[i],1);            if(Maxflow(s,t)==n)                r=mid;            else                l=mid+1;        }        printf("%d\n",r);    }    return 0;}
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