POJ 3256 Cow Picnic

题目大意：

题目链接

注释代码：

无注释代码：

#include <iostream>
#include <cstring>
#include <cstdio>
#include <queue>

#define	MAXK	100
#define	MAXN	1000
#define	MAXM	10000

using namespace std;

short	pos[MAXK + 1];
short	reach[MAXN + 1];
short	head[MAXN + 1];
short	to[MAXM + 1];
short	nxt[MAXM + 1];
bool	vis[MAXN + 1];
int		e;

queue<short>	que;

void
addarc( int u, int v ) {

	to[e] = v;

	nxt[e]  = head[u];
	head[u] = e++;
}

void
bfs(int s) {

	int		u, v;
	int		i;

	memset(vis, 0, sizeof(vis));

	vis[s] = true;
	que.push(s);
	while ( !que.empty() ) {
	
		reach[ u = que.front() ]++;
		que.pop();

		for ( i = head[u]; i; i = nxt[i] )
			if ( !vis[ v = to[i] ] ) {
			
				vis[v] = true;
				que.push(v);
			}
	}
}

int
main() {

	int		n, m, k;
	int		u, v;
	int		i;
	int		ans;

	ans = 0;
	e   = 1;

	scanf("%d%d%d", &k, &n, &m);
	for ( i = 1; i <= k; i++ ) scanf("%d", pos + i);
	while ( m-- ) {
	
		scanf("%d%d", &u, &v);
		addarc( u, v );
	}

	for ( i = 1; i <= k; i++ ) bfs( pos[i] );

	for ( i = 1; i <= n; i++ )
		if ( reach[i] == k )
			ans++;

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

	return 0;
}