标签：hdu dijkstra 图论 最短路
Choose the best route
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 10287 Accepted Submission(s): 3317
Problem Description
One day , Kiki wants to visit one of her friends. As she is liable to carsickness , she wants to arrive at her friend’s home as soon as possible . Now give you a map of the city’s traffic route, and the stations which are near Kiki’s
home so that she can take. You may suppose Kiki can change the bus at any station. Please find out the least time Kiki needs to spend. To make it easy, if the city have n bus stations ,the stations will been expressed as an integer 1,2,3…n.
Input
There are several test cases.
Each case begins with three integers n, m and s,(n<1000,m<20000,1=<s<=n) n stands for the number of bus stations in this city and m stands for the number of directed ways between bus stations .(Maybe there are several ways between two bus stations .) s stands
for the bus station that near Kiki’s friend’s home.
Then follow m lines ,each line contains three integers p , q , t (0<t<=1000). means from station p to station q there is a way and it will costs t minutes .
Then a line with an integer w(0<w<n), means the number of stations Kiki can take at the beginning. Then follows w integers stands for these stations.
Output
The output contains one line for each data set : the least time Kiki needs to spend ,if it’s impossible to find such a route ,just output “-1”.
Sample Input
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
Sample Output
从起点往终点找要多次调用函数，很容易超时～所以需要反着来～～只调用一次函数～～而且还要注意的是。。。路径是单向的～～
AC-code:
#include<cstdio>
#define max 0x3f3f3f3f
#define min(a,b) (a>b?b:a)
int n,dis[1005],cost[1005][1005];
void dijkstra(int a)
{
int vis[1005],i;
for(i=1;i<=n;i++)
{
dis[i]=max;
vis[i]=0;
}
dis[a]=0;
while(1)
{
int v=-1;
for(i=1;i<=n;i++)
if(!vis[i]&&(dis[i]<dis[v]||v==-1))
v=i;
if(v==-1)
break;
vis[v]=1;
for(i=1;i<=n;i++)
dis[i]=min(dis[i],dis[v]+cost[v][i]);
}
}
int main()
{
int so[1005],m,s,i,j,a,b,c;
while(~scanf("%d%d%d",&n,&m,&s))
{
int ans=max;
for(i=1;i<=n;i++)
for(j=1;j<=n;j++)
cost[i][j]=max;
while(m--)
{
scanf("%d%d%d",&a,&b,&c);
cost[b][a]=min(cost[b][a],c);
}
scanf("%d",&a);
dijkstra(s);
for(i=0;i<a;i++)
{
scanf("%d",&b);
ans=min(ans,dis[b]);
}
if(ans==max)
printf("-1\n");
else
printf("%d\n",ans);
}
return 0;
}
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HDU 2680：Choose the best route【Dijkstra】
标签：hdu dijkstra 图论 最短路
原文地址：http://blog.csdn.net/lin14543/article/details/47727285
