实在不知道上面的代码有什么问题...不过强烈推荐SPFA.又好写,又快的东西!

#include <cstdio>
#include <cstring>
#include <vector>
#include <utility>
using namespace std;
vector<pair<int,int> > g[505];
int path[505],queue[500001];
bool check[505];
int i,m,f,p,c,op,cl;
void read_graph()
{
	int i,a,b,s;
	scanf("%d %d %d %d",&f,&p,&c,&m);
	for (i=1;i<=p;i++)
	{
		scanf("%d %d %d",&a,&b,&s);
		g[a].push_back(make_pair(b,s));g[b].push_back(make_pair(a,s));
	}
}
void init()
{
	int i;
	memset(check,false,sizeof(check));
	memset(queue,false,sizeof(queue));
	for (i=1;i<=f;i++) path[i]=2147483647;
}
void do_SPFA()
{
	int temp,tempnode,i;
	op=1;cl=0;queue[1]=1;path[1]=0;check[1]=true;
	while (cl<op)
	{
		cl++;
		temp=queue[cl];
		for (i=0;i<g[temp].size();i++)
		{
			tempnode=g[temp][i].first;
			if (path[tempnode]>(path[temp]+g[temp][i].second))
			{
				path[tempnode]=path[temp]+g[temp][i].second;
				if (!check[tempnode]) {op++;queue[op]=tempnode;check[tempnode]=true;}
			}
		}
		check[temp]=false;
	}
}
void show_ans()
{
	int cow[105],total=0,i;
	for (i=1;i<=c;i++) 
	{
		scanf("%d",&cow[i]);
		if (path[cow[i]]<=m) total++;
	}
	printf("%d\n",total);
	for (i=1;i<=c;i++) if (path[cow[i]]<=m) printf("%d\n",i);
}
int main()
{
	read_graph();
	init();
	do_SPFA();
	show_ans();
}