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;
}