Choose the best route HDU杭电2680【dijkstra算法 || SPFA】

http://acm.hdu.edu.cn/showproblem.php?pid=2680

5 8 5
1 2 2
1 5 3
1 3 4
2 4 7
2 5 6
2 3 5
3 5 1
4 5 1
2
2 3
4 3 4
1 2 3
1 3 4
2 3 2
1
1

1
-1

//Dijkstra

#include<stdio.h>
#include<string.h>
#define INF 0x3f3f3f3f
int map[1010][1010];
int dis[20200];
bool used[20200];
int n;
int e;
int dijkstra()
{
	int i,j;
	memset(used,0,sizeof(used));
	for(i=0;i<=n;++i)
		dis[i]=INF;
	int pos;
	for(i=0;i<=n;++i)//第一次给dis赋值 
	{
		dis[i]=map[0][i];
	}
	dis[0]=0;
	used[0]=1;
	for(i=0;i<n;++i)//最多执行n次 
	{
		int min=INF;
		for(j=0;j<=n;++j)
		{
			if(!used[j]&&dis[j]<min)
			{
				min=dis[j];
				pos=j;
			}
		} 
		used[pos]=1;
		if(pos==e) return dis[pos];
		for(j=0;j<=n;++j)//把dis数组更新。也叫松弛
		{
			if(!used[j]&&dis[j]>map[pos][j]+dis[pos])
			{
				dis[j]=map[pos][j]+dis[pos];
			}
		}
	}
	return -1;
}
int main()
{
	int m,s,T;
	int u,v,w;
	int temp;
	int i,j;
	while(~scanf("%d%d%d",&n,&m,&e))
	{		
		for(i=0;i<=n;++i)
      		for(j=0;j<=i;++j)
        		map[i][j]=map[j][i]=INF;
		for(i=1;i<=m;++i)
		{
			scanf("%d%d%d",&u,&v,&w);
			if(map[u][v]>w)
				map[u][v]=w;
		}		
		scanf("%d",&T);
		for(i=1;i<=T;++i)
		{
			scanf("%d",&temp);
			map[0][temp]=0;//0指向要找的原点 
		}
		int ans=dijkstra();//万能源点0 
		if(ans==-1)printf("-1\n");
		else printf("%d\n",ans);
	}
	return 0;
}

//SPFA

#include <cstdio>
#include <cstring>
#include <queue>
#define MAXN 1100
#define MAXM 22000
#define INF 0x3f3f3f3f
using namespace std;
int map[MAXN][MAXN];
int vis[MAXN];//推断是否增加队列了 
int num;
int low[MAXM];//存最短路径 
int e;
int M, N;
void SPFA()
{
	int i, j;
	queue<int> Q;
	memset(low, INF, sizeof(low)); 
	memset(vis, 0, sizeof(vis));	
	vis[0] = 1;
	low[0] = 0;
	Q.push(0);
	while(!Q.empty())
	{
		int u = Q.front();
		Q.pop();
		vis[u] = 0;//出队列了。不在队列就变成0 
		for(i = 1; i <= N; ++i)
		{
			
			if(low[i] > low[u] + map[u][i])
			{
				low[i] = low[u] + map[u][i];
				if(!vis[i])				 
			 	{
			 		vis[i]=1;
			 		Q.push(i);
			 	}
			}
		}
	}
	if(low[e] == INF) printf("-1\n");
	else printf("%d\n",low[e]);
}
int main()
{
	int u, v, w;
	while(~scanf("%d%d%d", &N, &M, &e))
	{
		for(int i=0; i<=N;++i)
			for(int j=0;j<=i;++j)
				map[i][j]=map[j][i]=INF;
		while(M--)
		{
			scanf("%d%d%d", &u, &v, &w);
			if(map[u][v]>w)//一定要判重 
				map[u][v]=w;
//			map[u][v]=w;
//			map[v][u]=w;
		}
		int T,s;
		scanf("%d",&T);	
		while(T--)
		{
			scanf("%d",&s);
			map[0][s]=0;//万能源点 
		}	
		SPFA();
	}
	return 0;
}