16.图

构造上图的图
public class Graph {
    //定点集合
    private List<String> vertexList;
    //存储图对应的临结矩阵
    private int[][] edges;
    //表示边的数目
    private int numOfEdges;

    public static void main(String[] args) {
        String[] arr = {"A", "B", "C", "D", "E"};
        Graph graph = new Graph(arr.length);
        for (String value : arr) {
            graph.insertVertex(value);
        }
        //插入边：A-C A-B C-B B-E B-D 总计5条边
        graph.insertEdge(graph.getIndex("A"), graph.getIndex("C"), 1);
        graph.insertEdge(graph.getIndex("A"), graph.getIndex("B"), 1);
        graph.insertEdge(graph.getIndex("B"), graph.getIndex("C"), 1);
        graph.insertEdge(graph.getIndex("B"), graph.getIndex("E"), 1);
        graph.insertEdge(graph.getIndex("B"), graph.getIndex("D"), 1);
        graph.show();
    }

    public void show() {
        System.out.println("  "+vertexList);
        int i=0;
        for (int[] colum : edges) {
            System.out.print(vertexList.get(i++)+" ");
            System.out.println(Arrays.toString(colum));
        }
        System.out.println("边的数量："+numOfEdges);
    }

    /**
     * @param n 有几个节点
     */
    public Graph(int n) {
        this.vertexList = new ArrayList<>(n);
        this.edges = new int[n][n];
    }

    public int getIndex(String vertex) {
        return vertexList.indexOf(vertex);
    }

    /**
     * 插入节点
     *
     * @param vertex
     */
    public void insertVertex(String vertex) {
        vertexList.add(vertex);
    }

    /**
     * 插入边
     *
     * @param v1     节点对应的数字下标
     * @param v2     节点对应的数字下标
     * @param weight 权值，0代表不连接， 1代表连接
     */
    public void insertEdge(int v1, int v2, int weight) {
        //因为是无向图，所以正反都得赋值
        edges[v1][v2] = weight;
        edges[v2][v1] = weight;
        numOfEdges++;
    }
}
输出：
      [A, B, C, D, E]
    A [0, 1, 1, 0, 0]
    B [1, 0, 1, 1, 1]
    C [1, 1, 0, 0, 0]
    D [0, 1, 0, 0, 0]
    E [0, 1, 0, 0, 0]
    边的数量：5