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《算法》第四章部分程序 part 12

▶ 书中第四章部分程序，包括在加上自己补充的代码，图的几种补充数据结构，包括无向 / 有向符号图，有权边结构，有边权有向图

● 无向符号图

 1 package package01;
 2 
 3 import edu.princeton.cs.algs4.In;
 4 import edu.princeton.cs.algs4.StdIn;
 5 import edu.princeton.cs.algs4.StdOut;
 6 import edu.princeton.cs.algs4.Graph;
 7 import edu.princeton.cs.algs4.ST;
 8 
 9 public class class01
10 {
11     private ST<String, Integer> st;  // 字符串转索引
12     private String[] keys;           // 索引转字符串
13     private Graph graph;
14 
15     public class01(String filename, String delimiter)
16     {
17         st = new ST<String, Integer>();
18         for (In in = new In(filename); !in.isEmpty();)      // 收集符号，存入集合，编号
19         {
20             String[] a = in.readLine().split(delimiter);
21             for (int i = 0; i < a.length; i++)
22             {
23                 if (!st.contains(a[i]))
24                     st.put(a[i], st.size());
25             }
26         }
27         keys = new String[st.size()];
28         for (String name : st.keys())
29             keys[st.get(name)] = name;
30         graph = new Graph(st.size());
31         for (In in = new In(filename); in.hasNextLine();)   // 再读一次，建图
32         {
33             String[] a = in.readLine().split(delimiter);
34             int v = st.get(a[0]);
35             for (int i = 1; i < a.length; i++)
36             {
37                 int w = st.get(a[i]);
38                 graph.addEdge(v, w);
39             }
40         }
41     }
42 
43     public boolean contains(String s)
44     {
45         return st.contains(s);
46     }
47 
48     public int indexOf(String s)
49     {
50         return st.get(s);
51     }
52 
53     public String nameOf(int v)
54     {
55         return keys[v];
56     }
57 
58     public Graph graph()
59     {
60         return graph;
61     }
62 
63     public static void main(String[] args)
64     {
65         String filename = args[0];             // 输入符号图（邻接表）的文件名和分隔符
66         String delimiter = args[1];
67         class01 sg = new class01(filename, delimiter);
68         for (Graph graph = sg.graph(); StdIn.hasNextLine();)
69         {
70             String source = StdIn.readLine();   // 再输入需要查询的顶点
71             if (sg.contains(source))
72             {
73                 int s = sg.indexOf(source);
74                 for (int v : graph.adj(s))
75                     StdOut.println("   " + sg.nameOf(v));
76             }
77             else
78                 StdOut.println("input not contain '" + source + "'");
79         }
80     }
81 }

● 有向符号图，与无向情形仅有方法名不同

 1 package package01;
 2 
 3 import edu.princeton.cs.algs4.In;
 4 import edu.princeton.cs.algs4.StdIn;
 5 import edu.princeton.cs.algs4.StdOut;
 6 import edu.princeton.cs.algs4.Digraph;
 7 import edu.princeton.cs.algs4.ST;
 8 
 9 public class class01
10 {
11     private ST<String, Integer> st;  
12     private String[] keys;           
13     private Digraph graph;           
14 
15     public class01(String filename, String delimiter)
16     {
17         st = new ST<String, Integer>();    
18         for (In in = new In(filename); !in.isEmpty();)
19         {
20             String[] a = in.readLine().split(delimiter);
21             for (int i = 0; i < a.length; i++) 
22             {
23                 if (!st.contains(a[i]))
24                     st.put(a[i], st.size());
25             }
26         }        
27         keys = new String[st.size()];
28         for (String name : st.keys())
29             keys[st.get(name)] = name;        
30         graph = new Graph(st.size());
31         for (In in = new In(filename); in.hasNextLine();)   // 再读一次，建图
32         {
33             String[] a = in.readLine().split(delimiter);
34             int v = st.get(a[0]);
35             for (int i = 1; i < a.length; i++) 
36             {
37                 int w = st.get(a[i]);
38                 graph.addEdge(v, w);
39             }
40         }
41     }
42 
43     public boolean contains(String s)
44     {
45         return st.contains(s);
46     }
47 
48     public int indexOf(String s)
49     {
50         return st.get(s);
51     }
52          
53     public String nameOf(int v)
54     {    
55         return keys[v];
56     }
57 
58     public Digraph digraph()
59     {
60         return graph;
61     }
62     
63     public static void main(String[] args)
64     {
65         String filename = args[0];
66         String delimiter = args[1];
67         class01 sg = new class01(filename, delimiter);        
68         for (Digraph graph = sg.digraph(); StdIn.hasNextLine();)
69         {
70             String t = StdIn.readLine();
71             for (int v : graph.adj(sg.indexOf(t)))
72                 StdOut.println("   " + sg.nameOf(v));
73         }
74     }
75 }

● 有权边结构

 1 package package01;
 2 
 3 import edu.princeton.cs.algs4.StdOut;
 4 import edu.princeton.cs.algs4.Edge;
 5 
 6 public class class01 implements Comparable<Edge>
 7 {
 8     private final int v;
 9     private final int w;
10     private final double weight;
11 
12     public class01(int inputV, int inputW, double inputWeight)
13     {
14         if (inputV < 0 || inputW < 0 || Double.isNaN(inputWeight))
15             throw new IllegalArgumentException("
<Construtor> v < 0 || w < 0 || weight == NaN.
");
16         v = inputV;
17         w = inputW;
18         weight = inputWeight;
19     }
20 
21     public double weight()
22     {
23         return weight;
24     }
25 
26     public int either()
27     {
28         return v;
29     }
30 
31     public int other(int vertex)
32     {
33         if (vertex == v)
34             return w;
35         if (vertex == w)
36             return v;
37         throw new IllegalArgumentException("
<other> No such point.
");
38     }
39 
40     @Override
41         public int compareTo(class01 that)
42     {
43         return Double.compare(weight, that.weight);
44     }
45 
46     public String toString()
47     {
48         return String.format("%d-%d %.5f", v, w, weight);
49     }
50 
51     public static void main(String[] args)
52     {
53         class01 e = new class01(12, 34, 5.67);
54         StdOut.println(e);
55     }
56 }

● 有边权有向图

  1 package package01;
  2 
  3 import edu.princeton.cs.algs4.In;
  4 import edu.princeton.cs.algs4.StdOut;
  5 import edu.princeton.cs.algs4.StdRandom;
  6 import edu.princeton.cs.algs4.Bag;
  7 import edu.princeton.cs.algs4.Stack;
  8 import edu.princeton.cs.algs4.Edge;
  9 
 10 public class class01
 11 {
 12     private static final String NEWLINE = System.getProperty("line.separator");// 换行，按操作系统适配
 13 
 14     private final int V;
 15     private int E;
 16     private Bag<Edge>[] adj;
 17 
 18     public class01(int inputV)
 19     {
 20         if (inputV < 0)
 21             throw new IllegalArgumentException("
<Constructor> V < 0.
");
 22         V = inputV;
 23         E = 0;
 24         adj = (Bag<Edge>[]) new Bag[V];
 25         for (int v = 0; v < V; v++)
 26             adj[v] = new Bag<Edge>();
 27     }
 28 
 29     public class01(int inputV, int inputE)
 30     {
 31         this(inputV);
 32         if (inputE < 0)
 33             throw new IllegalArgumentException("
<Constructor> E < 0.
");
 34         for (int i = 0; i < E; i++)                 // 添加 E 条边，随机权重
 35         {
 36             int v = StdRandom.uniform(V);
 37             int w = StdRandom.uniform(V);
 38             Edge e = new Edge(v, w, Math.round(100 * StdRandom.uniform()) / 100.0);
 39             addEdge(e);
 40         }
 41     }
 42 
 43     public class01(In in)
 44     {
 45         this(in.readInt());
 46         E = in.readInt();
 47         if (E < 0)
 48             throw new IllegalArgumentException("
<Constructor> E < 0.
");
 49         for (int i = 0; i < E; i++)
 50         {
 51             int v = in.readInt();
 52             int w = in.readInt();
 53             Edge e = new Edge(v, w, in.readDouble());
 54             addEdge(e);
 55         }
 56     }
 57 
 58     public class01(class01 G)
 59     {
 60         this(G.V());
 61         E = G.E();
 62         for (int v = 0; v < G.V(); v++)
 63         {
 64             Stack<Edge> reverse = new Stack<Edge>();// 用栈保存原图遍历得到的边，吐栈是回复顺序
 65             for (Edge e : G.adj[v])
 66                 reverse.push(e);
 67             for (Edge e : reverse)
 68                 adj[v].add(e);
 69         }
 70     }
 71 
 72     public int V()
 73     {
 74         return V;
 75     }
 76 
 77     public int E()
 78     {
 79         return E;
 80     }
 81 
 82     public void addEdge(Edge e)
 83     {
 84         int v = e.either();
 85         int w = e.other(v);
 86         adj[v].add(e);
 87         adj[w].add(e);
 88         E++;
 89     }
 90 
 91     public Iterable<Edge> adj(int v)
 92     {
 93         return adj[v];
 94     }
 95 
 96     public int degree(int v)
 97     {
 98         return adj[v].size();
 99     }
100 
101     public Iterable<Edge> edges()
102     {
103         Bag<Edge> list = new Bag<Edge>();
104         for (int v = 0; v < V; v++)
105         {
106             boolean selfLoop = false;   // 注意两条自边只算一个自环
107             for (Edge e : adj(v))
108             {
109                 if (e.other(v) == v)
110                 {
111                     if (!selfLoop)
112                         list.add(e);
113                     selfLoop = !selfLoop;
114                 }
115                 if (e.other(v) > v)     // 索引控制，防止反复添加同一条边
116                     list.add(e);
117             }
118         }
119         return list;
120     }
121 
122     public String toString()
123     {
124         StringBuilder s = new StringBuilder();
125         s.append(V + " " + E + NEWLINE);
126         for (int v = 0; v < V; v++)
127         {
128             s.append(v + ": ");
129             for (Edge e : adj[v])
130                 s.append(e + "  ");
131             s.append(NEWLINE);
132         }
133         return s.toString();
134     }
135 
136     public static void main(String[] args)
137     {
138         In in = new In(args[0]);
139         class01 G = new class01(in);
140         StdOut.println(G);
141     }
142 }

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原文地址：https://www.cnblogs.com/cuancuancuanhao/p/9830097.html