https://www.luogu.org/problemnew/show/P3386#sub

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <algorithm>
 4 #include <cstring>
 5 
 6 int match[1005], lt[1005][1005], n, m, e, vis[1005];
 7 
 8 inline bool dfs(int u){
 9     for(int i = 1; i <= m; ++i){
10         if
 
(!vis[i] && lt[u][i]){
11             vis[i] = 1;
12             if (!match[i] || dfs(match[i])){
13                 match[i] = u;
14                 return true;
15             }
16         }
17     }
18     return false;
19 }
20 
21 int main(void){
22     int ans = 0;
23     scanf("
 
%d%d%d", &n, &m, &e);
24     for(int u, v, i = 1; i <= e; ++i){
25         scanf("%d%d", &u, &v); if (u <= n && v <= m){lt[u][v] = 1;}
26     }
27     for(int i = 1; i <= n; ++i){
28         memset(vis, 0, sizeof(vis));
29         if (dfs(i)) ans++;
30     }
 
31     printf("%d", ans);
32     
33     return 0;
34 }

[模板]二分圖匹配