软工个人项目——地铁最短路径

北京地铁线路图

Github

https://github.com/31701014/Subway

一、功能

读取一定格式的地铁线路txt文件

根据用户需求提供最优乘坐方案或地铁线路信息

二、文件格式

第一个字段为线路名，一行为一条线路，以空格分隔开

三、测试

查询线路：

查询最短路径：

错误输入：

四、算法设计

数据读入存储：

BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(new File("E:/subway.txt"))));
        String lineTxt = null;
        while ((lineTxt = br.readLine()) != null) {
            String na=null;
            String[] names = lineTxt.split(" ");
            String iid=names[0];
            for(int i=0;i<names.length-1;i++)
                names[i]=names[i+1];
            for (String namer : names) {                        
                if (map.keySet().contains(namer)) {
                    int temp=0;
                    for(int i=0;i<names.length;i++) {
                        if(namer.equals(names[i])) temp++;
                        }
                    if(temp==1) {
                        map.put(namer, (map.get(namer) + 1));
                        id.put(namer,id.get(namer)+","+iid);
                    }
                } else {
                    name[x] =namer;
                    x++;
                    map.put(namer, 1);
                    id.put(namer, iid);
                }
                if(na!=null) {
                    Map[n * list.indexOf(namer) + list.indexOf(na)] = 2;
                    Map[n * list.indexOf(na) + list.indexOf(namer)] = 2;        
                }
                na=namer;
            }
        }
        br.close();

站点及线路信息均保存在一维数组Map中

最短路径算法：

static double Dijkstra(double Map[], int path[], int n, int v, int d) {
        double min, ks;
        int u, t;
        double dist[] = new double[n + 1];
        int s[] = new int[n + 1];
        for (int i = 0; i < n; i++) {
            dist[i] = Map[n * v + i];
            s[i] = 0;
            if (i != v && dist[i] < MaxInt) {
                path[i] = v;
            } else
                path[i] = -1;
        }
        s[v] = 1;
        for (int i = 0; i < n - 1; i++) {
            min = MaxInt;
            u = v;
            for (int j = 0; j < n; j++) {
                if (s[j] == 0 && dist[j] < min) {
                    u = j;
                    min = dist[j];
                }
            }
            s[u] = 1;
            for (t = 0; t < n; t++) {
                if (s[t] == 0 && dist[u] + Map[n * u + t] < dist[t]) {
                    dist[t] = (float) (dist[u] + Map[n * u + t]);
                    path[t] = u;
                }
            }
        }

        ks = dist[d];// 现在只返回人要的那个目的值
        return ks;
    } // Dijkstra算法内容

输出及交互：

String start, dest,road;
        double race = 21;
        System.out.print("请输入操作（查询线路为a，查询最短路径为b）:");
        Scanner cin = new Scanner(System.in);
        String temp=cin.nextLine();
        if(temp.equals("a")) {
            System.out.print("请输入查询线路:");
            road = cin.nextLine();
            try {
                BufferedReader bw = new BufferedReader(new InputStreamReader(new FileInputStream(new File("E:/subway.txt"))));
            String line = null;
            int have=0;
            while ((line = bw.readLine()) != null) {
                String[] names = line.split(" ");
                String iid=names[0];            
                if(iid.equals(road)) {
                    have=1;
                for (String namer : names) {
                    if(id.get(namer)!=null) {
                    System.out.println(namer+"("+id.get(namer)+")");
                    }
                }
            }           
        }
            if(have==0) System.out.println("线路不存在");
            bw.close();
            }catch (Exception e) {
                System.err.println("错误");
            }
        }
        else if(temp.equals("b")) {
        System.out.print("请输入起点站名:");
        start = cin.nextLine();
        while (!IsT(name, start, n)) {
            System.out.print("输入错误，请重新输入起点站名:");
            start = cin.nextLine();
        }
        System.out.print("请输入终点站名:");
        dest = cin.nextLine();
        while (!IsT(name, dest, n)) {
            System.out.print("输入错误，请重新输入终点站名:");
            dest = cin.nextLine();
        }
        if (IsT(name, dest, n)) {
            float distan = (float) Dijkstra(Ma, pa, n, Check(nam, start, n), Check(nam, dest, n));// 能查出此结点到其他点最短路径
            int s, d;
            s = Check(nam, start, n);
            d = Check(nam, dest, n);
            stanum = 0;
            print(pa, nam, s, d);
            System.out.println(stanum + " " + dest);
            int fen = (int) (distan * 1000 / race / 60);
            int miao = ((int) (distan * 1000 / race)) % 60;
            int r;
            if (distan > 6) {
                if (distan > 12) {
                    if (distan > 32) {
                        r = (int) (6 + distan / 20);
                    } else
                        r = (int) (4 + distan / 10);
                } else
                    r = 4;
            } else
                r = 3;

            System.out.println("总运行距离为:" + distan + "km");
            System.out.println("途径总站点数为:" + stanum);
            System.out.println("运行时间" + fen + "分" + miao + "秒");
            System.out.println("总票价为:" + r + "元");

        } else {
            System.out.println();
            System.out.println("please choise your stations!");
            }
        }
        return;

五、总结

本次个人项目在数据的存储方法上遇到了困难，参考了网上的一些代码和思想，采用了使用一维数组存储的特殊方法。本次个人作业提升了自己的编程思想和逻辑思维也熟悉了GitHub等的使用。