Hdu2063 get on the bus [Hungary]

Students go to the roller coaster, but to do the roller coaster, they must be a male student and a female student,

Now I want to tell you how many students can ride on a roller coaster with each other.

Both men and women <= 500

 

Ideas:

Connect a female student with a favorite male student, and then find the maximum matching of the Bipartite Graph.

You can also use the largest stream to create an edge with a capacity of 1 between the source site and the female students, and create an edge with a capacity of 1 for both the female students and their favorite male students, finally, we will establish a Jike with a capacity of 1 between the male and the sink, and find the maximum Liu.

 

The Hungary algorithm, which is stored directly by the number of people using the adjacent matrix.

Code:

 1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4 using namespace std; 5  6 const int maxn = 505; 7 bool G[maxn][maxn]; 8 int Left[maxn]; 9 bool vis[maxn];10 int n, m;11 12 bool Find(int u) {13     for(int i = 1; i <= m; i++) {14         if(G[u][i] && !vis[i]) {15             vis[i] = true;16             if(Left[i] == -1 || Find(Left[i])) {17                 Left[i] = u;18                 return true;19             }20         }21     }22     return false;23 }24 25 void solve() {26     int num = 0;27     memset(Left, -1, sizeof(Left));28     for(int i = 1; i <= n; i++) {29         memset(vis, 0, sizeof(vis));30         if(Find(i)) num++;31     }32     printf("%d\n",num);33 }34 35 int main() {36     int k;37     int u, v;38    // freopen("a.txt","r",stdin);39     while(scanf("%d",&k) && k) {40         scanf("%d %d",&n, &m);41         memset(G, false, sizeof(G));42         for(int i = 0; i < k; i++) {43             scanf("%d %d",&u, &v);44             G[u][v] = 1;45         }46         solve();47     }48     return 0;49 }

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