引出匈牙利算法：

int find(int x, int n){
	int i;
	for(i = 1; i <= n; i++){
		if(!vis[i] && map[x][i]){ //依次判断女生是否对男生有好感
			vis[i] = 1;
			if(pri[i] == -1 || find(pri[i], n)){ 
				pri[i] = x;
				return 1;
			}
		}
	}
	return 0;
}

具体见：https://blog.csdn.net/dark_scope/article/details/8880547

#include<stdio.h>
#include<string.h>
#define maxn 505
int map[maxn][maxn];
int pri[maxn];
int vis[maxn];
int find(int x, int n);
int main()
{
	int k, m, n;
	while(~scanf("%d", &k) && k){
		scanf("%d %d", &m, &n);
		int i, a, b, ans = 0;
		
		memset(map, 0, sizeof(map));
		memset(pri, -1, sizeof(pri));
		for(i = 1; i <= k; i++){ 
			scanf("%d %d", &a, &b);
			map[a][b] = 1;
		}
		for(i = 1; i <= m; i++){
			memset(vis, 0, sizeof(vis));
			if(find(i, n))
				ans++;
		}
		printf("%d\n", ans);	
	}
	return 0;
}
int find(int x, int n){
	int i;
	for(i = 1; i <= n; i++){
		if(!vis[i] && map[x][i]){ //依次判断女生是否对男生有好感
			vis[i] = 1;
			if(pri[i] == -1 || find(pri[i], n)){ 
				pri[i] = x;
				return 1;
			}
		}
	}
	return 0;
}

直接贴个代码，等懂了再回来看

较为清晰的思路：https://blog.csdn.net/thestarfish/article/details/46928267