hdu 2680 Choose the best route

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

简单最短路问题。。。。。

运行结果：

Accepted

2680

265MS

4164K

1382 B

C++

//dijkstra
#include<stdio.h>
#define INF (1<<30)
#define MAXN 1005
int map[MAXN][MAXN],n,m,s,d[MAXN],dis[MAXN];
bool vis[MAXN];
void dijkstra(int start)
{
	int i,j,k;
	for(i = 1; i <= n; i++)//初始化所有点为未访问过，起点到所有其他点的距离为无穷远
		vis[i] = false,dis[i] = INF;
	//将起点到个顶点的距离保存在dis数组中
	for(i = 1; i <= n; i++)
		dis[i] = map[start][i];
	//起点到其本身的距离为0，并将其标记为已经访问过
	dis[start] = 0;
	vis[start] = true;
	//在将n-1个顶点加入到最短路中
	for(i = 1; i < n; i++)
	{
		int min = INF;
		for(j = 1; j <= n; j++)
		{
			if(!vis[j] && dis[j] < min)
			{
				min = dis[j];
				k = j;
			}
		}
		if(min == INF)
			continue;
		vis[k] = true;
		for(j = 1; j <= n; j++)
		{
			if( !vis[j] && dis[j] > min + map[k][j])
				dis[j] = min + map[k][j];
		}
	}
}
int main()
{
	int i,j,start,end,cost,w;
	while(scanf("%d%d%d",&n,&m,&s) != EOF)
	{
		for(i = 0; i <= n; i++)
			for(j = 0; j <= n; j++)
			{
				map[i][j] = (i == j ? 0 : INF);
			}
		for(i = 0; i < m; i++)
		{
			scanf("%d%d%d",&end,&start,&cost);
			if(map[start][end] > cost)
				map[start][end] = cost;
		}
		dijkstra(s);
		scanf("%d",&w);
		int min = INF;
		while( w-- )
		{
			scanf("%d",&end);
			if(dis[end] < min)
				min = dis[end];
		}
		if(min == INF)
			printf("-1\n");
		else
			printf("%d\n",min);
	}
	return 0;
}

运行结果：

Accepted

2680

125MS

496K

1270 B

C++

//spfa
#include<cstdio>
#include<cstring>
#include<queue>
using namespace std;
#define INF (1<<30)
struct node
{
	int v,cost;
	node *next;
}*head[1005],edge[20005];
int dis[1005];
bool vis[1005];
int n,m,s;
queue<int> que;
void spfa(int start)
{
	int i = 0;
	for(i = 1; i <= n; i++)
		dis[i] = INF;
	memset(vis,false,sizeof(vis));
	vis[start] = true;
	dis[start] = 0;
	que.push(start);
	while( !que.empty() )
	{
		int now = que.front();
		que.pop();
		vis[now] = false;
		for(node *p = head[now]; p ; p = p->next)
		{
			if(dis[p->v] > dis[now] + p->cost)
			{
				dis[p->v] = dis[now] + p->cost;
				if( !vis[p->v])
				{
					vis[p->v] = true;
					que.push(p->v);
				}
			}
		}
	}
}
int main()
{
	int i,start,end,cost,w,min;
	node *p;
	while(scanf("%d%d%d",&n,&m,&s) != EOF)
	{
		for(i = 1; i <= n; i++)
			head[i] = NULL;
		 p = edge;
		for(i = 0; i < m; i++)
		{
			scanf("%d%d%d",&start,&end,&cost);
			p->v = start;p->cost = cost;
			p->next = head[end];
			head[end] = p++;
		}
		spfa(s);
		scanf("%d",&w);
		min = INF;
		while( w-- )
		{
			scanf("%d",&start);
			if(dis[start] < min)
				min = dis[start];
		}
		if(min == INF)
			printf("-1\n");
		else
			printf("%d\n",min);
	}
	return 0;
}