地铁线路的简单规划——总结

GitHub

https://github.com/silkworm4379/subway_line

项目简介

实现北京地铁线路乘坐的最少站点查询。

实现语言：Java

开发环境：win10 Intellij IDEA

项目内容

TXT文件格式

总共需要两个TXT文件，一个存储线路，一个存储换站信息

 

 

结构

 

结构是用邻接表和点集信息，点集信息中存储换站有关信息

 

 

 1 public class AMGraph {
 2     String[] vexs = null;//点集信息
 3     public int[][] distance = null;//int[][] arr =new int[3][5]
 4     public int [][] matrix_dist=null;//距离矩阵
 5     public int [][] matrix_path=null;//路径矩阵
 6 }
 7 
 8 public class line {
 9     public ArrayList l=null;
10 }
11 
12 public class Vexs {
13     public static int vnumber=0;
14     public static String line_result=null;
15     
16     public line [] x=null;
17     public ArrayList  stationmap=null;
18     public Map mapline =null;
19     
20     public ArrayList  station=null;
21     public Map map =null;       //数据采用的哈希表结构
22 
23     public Vexs(){
24 
25     }
26 
27     public Vexs(String [] station){
28         int num=0;
29         num=station.length;
30         this.station=new ArrayList(num);
31         for(int i=0;i){
32             this.station.set(i,station[i]);
33         }
34 
35     }
36 
37 }

 

 

读取程序完成main函数功能

 1     public static void Read(String fileName,String fileName2) {
 2         Scanner input=new Scanner(System.in);
 3         File file = new File(fileName);
 4         Vexs v=new Vexs();
 5         AMGraph g=new AMGraph();
 6         try {
 7             System.out.println("以字符为单位读取文件内容，一次读多个字节：");
 8 
 9             BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(file), "UTF-8"));
10             String s=null;
11             ArrayList arraylist=new ArrayList();
12             v.map = new HashMap();
13             while ((s = br.readLine()) != null&&!s.equals("")) {//使用readLine方法，一次读一行
14                 String[] splitted = s.split(" ");
15                 arraylist.add(splitted[0]);
16                 arraylist.add(splitted[1]);
17             }
18             v.station = new ArrayList<>(new LinkedHashSet<>(arraylist));
19             for(int i=0;i){
20                 v.map.put(v.station.get(i),i);
21             }
22             br.close();
23             //读入转站信息
24             File file1=new File(fileName2);
25             v.mapline=new HashMap();
26             StringBuilder result2 = new StringBuilder();
27             BufferedReader br2 = new BufferedReader(new InputStreamReader(new FileInputStream(file1), "UTF-8"));
28             v.x=new line[500];
29             ArrayList arraylist2=new ArrayList();
30             while ((s = br2.readLine()) != null&&!s.equals("")) {//使用readLine方法，一次读一行
31                 String[] splitted = s.split(" ");
32                 v.x[Vexs.vnumber]=new line();
33                 v.x[Vexs.vnumber].l=new ArrayList();
34                 for(int j=0;j){
35                     if(j==0){
36                         arraylist2.add(splitted[j]);
37                     }
38                     else{
39                         v.x[Vexs.vnumber].l.add(splitted[j]);
40                     }
41 
42 
43                 }
44                 Vexs.vnumber++;
45             }
46             v.stationmap = new ArrayList<>(new LinkedHashSet<>(arraylist2));
47             for(int i=0;i){
48                 v.mapline.put(v.stationmap.get(i),i);
49             }
50             br2.close();
51             
52 
53             g.distance=new int[v.station.size()][v.station.size()];
54             g.matrix_dist=new int[v.station.size()][v.station.size()];
55             g.matrix_path=new int[v.station.size()][v.station.size()];
56             for(int i=0;i){
57                 int a=v.map.get(arraylist.get(i));
58                 int b=v.map.get(arraylist.get(i+1));
59                 g.distance[a][b]=1;
60                 g.distance[b][a]=1;
61             }
62         } catch (Exception e1) {
63             e1.printStackTrace();
64         }
65 
66         System.out.println("请输入两个站点的名称（站点之间加空格）：");
67         String a=input.next();
68         String b=input.next();
69 
70         floyd(g,v,a,b);
71         ArrayList result=getPath(g,v,a,b);
72         String before=new String(v.station.get(result.get(result.size()-1)));
73         String after=new String(v.station.get(result.get(result.size()-1)));
74         String now=new String(v.station.get(result.get(result.size()-1)));
75         int needchange=0;
76         for(int i=result.size()-1;i>=0;i--){
77             if(i>1&&i));
78             now=v.station.get(result.get(i));
79             if(isChange(g, v, before,after)&&i>1&&i){
80                 needchange=1;
81             }
82 
83             if(needchange==1&&i){
84                 if(has(g, v, v.station.get(result.get(i-1)), v.station.get(result.get(i-2)))){
85                     System.out.println("转站"+Vexs.line_result);
86                 }
87             }
88 
89             before=v.station.get(result.get(i));
90             System.out.print(v.station.get(result.get(i))+" ");
91             needchange=0;
92 
93 
94         }
95     }

 

用Floyd算法实现功能

    public static void floyd(AMGraph g,Vexs v,String a,String b){

        for (int i=0;i< v.station.size();i++)
            for (int j = 0; j < v.station.size(); j++)
            {
                g.matrix_dist[i][j] = g.distance[i][j];//初始化距离矩阵
                g.matrix_path[i][j] = i;//初始化路径矩阵
            }
        int temp=0;
        //三重循环
        for (int k = 0; k < v.station.size(); k++) {
            for (int i = 0; i < v.station.size(); i++) {
                for (int j = 0; j < v.station.size(); j++) {
                    if (g.matrix_dist[i][k] != 0 && g.matrix_dist[k][j] != 0)
                        if ((temp = g.matrix_dist[i][k] + g.matrix_dist[k][j]) < g.matrix_dist[i][j] || g.matrix_dist[i][j] == 0) {
                            //更新距离和路径
                            g.matrix_dist[i][j] = temp;
                            g.matrix_path[i][j] = g.matrix_path[k][j];
                        }
                }
            }
        }

    }

 

读取路径方法

 1     public static ArrayList getPath(AMGraph g,Vexs v,String a,String b){
 2         int k;
 3         k = v.map.get(b);
 4         ArrayList res=null;
 5         if (g.matrix_dist[v.map.get(a)][v.map.get(b)] == 0){
 6             return res;
 7         }
 8         res=new ArrayList();
 9         while (k != v.map.get(a)){
10             res.add(k);
11             k = g.matrix_path[v.map.get(a)][k];
12         }
13         res.add(k);
14 
15         return res;
16     }

 

换站有关方法

 1     public static boolean isChange(AMGraph g,Vexs v,String a,String b){
 2         if(has(g, v, a, b)){
 3             return false;
 4         }
 5         
 6         return true;
 7     }
 8 
 9     public static boolean has(AMGraph g,Vexs v,String a,String b){
10         for(int i=0;i){
11             for(int j=0;j){
12                 if(v.x[v.mapline.get(a)].l.get(i).equals(v.x[v.mapline.get(b)].l.get(j))){
13                     Vexs.line_result=v.x[v.mapline.get(a)].l.get(i);
14                     return true;
15                 }
16             }
17             
18         }
19         
20         return false;
21     }

 

个人总结

　　这个项目处理起来还算简单，在最后打印换站信息的时候被小坑了一把，变量名设置得太相似导致用错变量。其次存储格式有些冗余，完全可以去掉一部分信息，手动输入十分麻烦。