二分圖最大匹配.

#include <stdio.h>
#include <string.h>

#define MAX 505

bool map[MAX][MAX];
bool visited[MAX];
int match[MAX];
int k, n, m;

bool dfs(int v) {
	int i;

	for (i = 1; i <= m; i++) {
		if (map[v][i] && !visited[i]) {
			visited[i] = true;
			if (match[i] == -1 || dfs(match[i])) {
				match[i] = v;
				return true;
			}
		}
	}

	return false;
}

int main() {
	int i;
	int a, b;
	int ans;

	while (scanf("%d", &k) != EOF && k) {
		memset(map, false, sizeof(map));
		for (i = 0; i < MAX; i++) {
			match[i] = -1;
		}

		scanf("%d%d", &n, &m);
		for (i = 0; i < k; i++) {
			scanf("%d%d", &a, &b);
			map[a][b] = true;
		}

		ans = 0;
		for (i = 1; i <= n; i++) {
			memset(visited, false, sizeof(visited));
			if (dfs(i)) {
				ans++;
			}
		}

		printf("%d\n", ans);
	}

	return 0;
}