hdu1690Bus System

本文讨论了城市公交系统中如何通过已知距离成本关系计算两点间最短路径的问题,采用迪杰斯特拉算法解决。通过输入案例,演示了如何通过不同距离范围内的成本计算来确定两个公交站点间的最小费用。

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这个题目不是蛮难,第一次接触最短路,这个题目最开始我敲的一直没有输出,最后我索性重敲了一遍。。。结果就出来了。。哎,看来又是纠结的时候索性重敲一遍。。这题要用—int64,最后memset赋值原理是根据字节赋值的。。

Bus System

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 5938    Accepted Submission(s): 1511


Problem Description
Because of the huge population of China, public transportation is very important. Bus is an important transportation method in traditional public transportation system. And it’s still playing an important role even now.
The bus system of City X is quite strange. Unlike other city’s system, the cost of ticket is calculated based on the distance between the two stations. Here is a list which describes the relationship between the distance and the cost.



Your neighbor is a person who is a really miser. He asked you to help him to calculate the minimum cost between the two stations he listed. Can you solve this problem for him?
To simplify this problem, you can assume that all the stations are located on a straight line. We use x-coordinates to describe the stations’ positions.
 

Input
The input consists of several test cases. There is a single number above all, the number of cases. There are no more than 20 cases.
Each case contains eight integers on the first line, which are L1, L2, L3, L4, C1, C2, C3, C4, each number is non-negative and not larger than 1,000,000,000. You can also assume that L1<=L2<=L3<=L4.
Two integers, n and m, are given next, representing the number of the stations and questions. Each of the next n lines contains one integer, representing the x-coordinate of the ith station. Each of the next m lines contains two integers, representing the start point and the destination.
In all of the questions, the start point will be different from the destination.
For each case,2<=N<=100,0<=M<=500, each x-coordinate is between -1,000,000,000 and 1,000,000,000, and no two x-coordinates will have the same value.
 

Output
For each question, if the two stations are attainable, print the minimum cost between them. Otherwise, print “Station X and station Y are not attainable.” Use the format in the sample.
 

Sample Input
2 1 2 3 4 1 3 5 7 4 2 1 2 3 4 1 4 4 1 1 2 3 4 1 3 5 7 4 1 1 2 3 10 1 4
 

Sample Output
Case 1: The minimum cost between station 1 and station 4 is 3. The minimum cost between station 4 and station 1 is 3. Case 2: Station 1 and station 4 are not attainable.
 
#include<cstdio>
#include<cstring>
#define INF 0x3fffffffffffff
__int64  a[510],n;
__int64  vis[105],e[105][105];
__int64 d[105];
 void dijkstra(__int64 x)
 {
     __int64 i,j,now,tmp;
     memset(vis,0,sizeof(vis));
     memset(d,0x3f,sizeof(d));
     d[x]=0;
     for(i=1;i<=n;i++)
     {
         tmp=INF;
              for(j=1;j<=n;j++)
              {
                  if(!vis[j]&&tmp>d[j])
                  {
                      tmp=d[j];
                      now=j;
                  }//选出权值最小的节点now
              }
              vis[now]=1;//进行标记,将点加进来
              if(tmp==INF) break;
              for(j=1;j<=n;j++)
              {
                  if(d[j]>d[now]+e[now][j])
                    d[j]=d[now]+e[now][j];//更新从出发的所有边,跟新边的值
              }
     }
 }


 int main()
 {
      __int64 l[5],c[5];
       __int64  T,m,u,v;
        __int64 dis,i,j;
       __int64 cas=0;
       scanf("%I64d",&T);
       while(T--)
       {
           for(i=1;i<=4;i++)
             scanf("%I64d",&l[i]);
             for(i=1;i<=4;i++)
              scanf("%I64d",&c[i]);
             scanf("%I64d%I64d",&n,&m);
              for(i=1;i<=n;i++)
                scanf("%I64d",&a[i]);
              for(i=1;i<n;i++)
                for(j=i+1;j<=n;j++)
              {
                  dis=((a[i]-a[j])>0?(a[i]-a[j]):(a[j]-a[i]));
                    if(dis>0&&dis<=l[1])
                        e[i][j]=e[j][i]=c[1];
                    else if(dis>l[1]&&dis<=l[2])
                        e[i][j]=e[j][i]=c[2];
                    else if(dis>l[2]&&dis<=l[3])
                        e[i][j]=e[j][i]=c[3];
                    else if(dis>l[3]&&dis<=l[4])
                        e[i][j]=e[j][i]=c[4];
                    else if(dis>l[4])
                        e[i][j]=e[j][i]=INF;
              }
              printf("Case %I64d:\n",++cas);
              for(i=1;i<=m;i++)
              {
                scanf("%I64d%I64d",&u,&v);
                dijkstra(u);
                if(d[v]==INF)
                printf("Station %I64d and station %I64d are not attainable.\n", u,v);
                else
                printf("The minimum cost between station %I64d and station %I64d is %I64d.\n",u,v,d[v]);
               }
        }
        return 0;
 }


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