关于二分图匹配的讲解请看我之前的那篇博客。
1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4 #define maxn 1005 5 using namespace std; 6 struct Edge{ 7 int from,to; 8 }; 9 inline int read(){ 10 int num = 0; 11 char c; 12 bool flag = false; 13 while ((c = getchar()) == ' ' || c == ' ' || c == ' '); 14 if (c == '-') 15 flag = true; 16 else 17 num = c - '0'; 18 while (isdigit(c = getchar())) 19 num = num * 10 + c - '0'; 20 return (flag ? -1 : 1) * num; 21 } 22 Edge edge[maxn*maxn]; 23 int head[maxn*2]; 24 int tot = 0; 25 void add_edge(int from,int to){ 26 edge[++tot].from = head[from]; 27 edge[tot].to = to; 28 head[from] = tot; 29 } 30 int n,m,e; 31 bool vis[maxn]; 32 int match[maxn]; 33 bool dfs_xyl(int x){ 34 for (int i=head[x];i;i=edge[i].from){ 35 int v = edge[i].to; 36 if (!vis[v]){ 37 vis[v] = true; 38 if (!match[v]||dfs_xyl(match[v])){ 39 match[v] = x; 40 return true; 41 } 42 } 43 } 44 return false; 45 } 46 int main(){ 47 n = read();m = read();e = read(); 48 for (int i=1;i<=e;i++){ 49 int u,v; 50 u = read();v = read(); 51 if (u > n || v > m) 52 continue; 53 add_edge(u,v); 54 55 } 56 int ans = 0; 57 for (int i=1;i<=n;++i){ 58 memset(vis,false,sizeof(vis)); 59 if(dfs_xyl(i)) 60 ans++; 61 } 62 cout << ans << endl; 63 return 0; 64 }