【LA3415 训练指南】保守的老师 【二分图最大独立集，最小割】

  1 #include <cstdio>
  2 #include <algorithm>
  3 #include <cstring>
  4 #include <iostream>
  5 #include <cmath>
  6 #include <queue>
  7 
  8 using namespace std;
  9 const int maxn=1000+10;
 10 const int maxm=2000000+100;
 11 
 12 const int INF=2147000000;
 13 struct Dinic{
 14     int head[maxn],Next[maxm],to[maxm],cap[maxm],flow[maxm];
 15     int sz,n,m,s,t;
 16     bool vis[maxn];
 17     int cur[maxn],d[maxn];
 18     void init(int n){
 19         this->n=n;
 20         memset(head,-1,sizeof(head));
 21         this->sz=-1;
 22     }
 23     void add_edge(int a,int b,int c){
 24         ++sz;
 25         to[sz]=b;
 26         cap[sz]=c;flow[sz]=0;
 27         Next[sz]=head[a];head[a]=sz;
 28         ++sz;
 29         to[sz]=a;
 30         cap[sz]=c;flow[sz]=c;
 31         Next[sz]=head[b];head[b]=sz;
 32     }
 33     bool BFS(){
 34         memset(vis,0,sizeof(vis));
 35         queue<int>Q;
 36         vis[s]=1;
 37         d[s]=0;
 38         Q.push(s);
 39         while(!Q.empty()){
 40             int u=Q.front();Q.pop();
 41             for(int i=head[u];i!=-1;i=Next[i]){
 42                 int v=to[i];
 43                 if(!vis[v]&&cap[i]>flow[i]){
 44                     vis[v]=1;
 45                     d[v]=d[u]+1;
 46                     Q.push(v);
 47                 }
 48             }
 49         }
 50         return vis[t];
 51    }
 52     int DFS(int x,int a){
 53         if(x==t||a==0)return a;
 54         int Flow=0,f;
 55         for(int& i=cur[x];i!=-1;i=Next[i]){
 56             int v=to[i];
 57             if(d[v]==d[x]+1&&(f=DFS(v,min(a,cap[i]-flow[i])))>0){
 58                 Flow+=f;
 59                 flow[i]+=f;
 60                 flow[i^1]-=f;
 61                 a-=f;
 62                 if(a==0)break;
 63             }
 64         }
 65         return Flow;
 66     }
 67     int Maxflow(int s,int t){
 68         this->s=s,this->t=t;
 69         int Flow=0;
 70         while(BFS()){
 71             for(int i=0;i<=n;i++)
 72              cur[i]=head[i];
 73 
 74             Flow+=DFS(s,INF);
 75         }
 76         return Flow;
 77     }
 78 }dinic;
 79 int T,n;
 80 int high[maxn];
 81 char sex[maxn];
 82 string mus[maxn],phy[maxn];
 83 int main(){
 84     scanf("%d",&T);
 85     for(int t=1;t<=T;t++){
 86         scanf("%d",&n);
 87         for(int i=1;i<=n;i++){
 88             scanf("%d %c",&high[i],&sex[i]);
 89             cin>>mus[i]>>phy[i];
 90         }
 91         dinic.init(n+2);
 92         for(int i=1;i<=n;i++){
 93             if(sex[i]==‘M‘){
 94                 for(int j=1;j<=n;j++){
 95                     if(sex[j]==‘F‘&&abs(high[i]-high[j])<=40&&mus[i]==mus[j]&&phy[i]!=phy[j]){
 96                             dinic.add_edge(i,j,1);
 97                     }
 98                 }
 99             }
100         }
101         for(int i=1;i<=n;i++){
102             if(sex[i]==‘M‘)
103                 dinic.add_edge(0,i,1);
104         }
105         for(int i=1;i<=n;i++){
106             if(sex[i]==‘F‘)
107                 dinic.add_edge(i,n+1,1);
108         }
109         int ans=dinic.Maxflow(0,n+1);
110         printf("%d\n",n-ans);
111     }
112 return 0;
113 }