cow and stall poj 1274

 1 #include<iostream>
 2 #include<set>
 3 #include<vector>
 4 using namespace std;
 5 int path(int cow, vector<set<int> >& cowToStall, vector<int>& matchStallToCow, set<int>& visited){
 6     for(set<int>::iterator it = cowToStall[cow].begin(); it != cowToStall[cow].end(); it++){
 7         int stall = *it;
 8         if(visited.find(stall) != visited.end()) continue ;
 9         visited.insert(stall);
10         if(matchStallToCow[stall] == 0 || path(matchStallToCow[stall], cowToStall, matchStallToCow, visited)){
11             matchStallToCow[stall] = cow;
12             return 1;
13         }
14     }
15     return 0;
16 }
17 int main()
18 {
19     int n, m;
20     while(cin>>n>>m){
21         vector<set<int> > cowToStall(n + 1);
22         vector<int> matchStallToCow(m + 1, 0);
23         for(int i = 1; i <= n; i++){
24             int count, j;
25             cin>>count;
26             for(int k = 0; k < count; k++){
27                 cin>>j;
28                 cowToStall[i].insert(j);
29             }
30         }
31         int ans = 0;
32         for(int i = 1; i <= n; i++){
33             set<int> visited;
34             ans += path(i, cowToStall, matchStallToCow, visited);
35         }
36         cout<<ans<<endl;    
37     }
38     return 0;
39 }