bzoj1574

只要把不能过的周围的点都不能过再dfs一遍就好了。。好像有点贪心的味道

#include<iostream>
#include<algorithm>
#include<cstdio>
#include<queue>
using namespace std;
struct edgee
{
	int from, to;
	edgee(int f, int t) :from(f), to(t)
	{}
	edgee()
	{}
};
edgee edge[400020];
int edgetot;
int first[30010], nextt[400020];
bool isgo[30010];
void addedge(int from, int to)
{
	nextt[edgetot] = first[from];
	edge[edgetot] = edgee(from, to);
	first[from] = edgetot++;
	nextt[edgetot] = first[to];
	edge[edgetot] = edgee(to, from);
	first[to] = edgetot++;
}
int P, C, N;
int anss = 0;
void dfs(int now, int from)
{
	anss++; isgo[now] = 1;
	for (int i = first[now]; i != -1; i = nextt[i])
	{
		int to = edge[i].to;
		if (isgo[to] != 1 )
		{
			dfs(to, now);
		}
	}
}
int main()
{
	scanf("%d%d%d", &P, &C, &N);
	for (int i = 0; i <= P; i++)
		first[i] = -1;
	for (int i = 0; i < C; i++)
	{
		int a, b;
		scanf("%d%d", &a, &b);
		addedge(a, b);
	}
	for (int i = 1; i <= N; i++)
	{
		int k;
		scanf("%d", &k);
		isgo[k] = 1;
		for (int j = first[k]; j != -1; j = nextt[j])
		{
			int to = edge[j].to;
			isgo[to] = 1;
		}
	}
	dfs(1, 1);
	printf("%d\n", P - anss);
	return 0;
}