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。