Java程序，使用DFS和用户提供的邻接矩阵，在无向图中显示连接的组合的数量

Question

如标题所述，我需要创建一个Java程序，该程序将使用用户提供的邻接矩阵来计算无向图内有多少个连接的组件。 我花了很多时间并成功地获得了邻接矩阵，并计算出有多少个顶点未连接到“源”顶点。 但是，我无法打包并计算连接的组件。 对我来说太难了。 请帮助，谢谢。 这是我的代码的当前状态：

import java.util.InputMismatchException;
import java.util.Scanner;
import java.util.Stack;
import java.util.Arrays;

public class UndirectedConnectivityDfs
{
    private Stack<Integer> stack;

    public UndirectedConnectivityDfs() 
    {
        stack = new Stack<Integer>();
    } 

    public void dfs(int adjacency_matrix[][], int source)
    {
        int number_of_nodes = adjacency_matrix[source].length - 1;  
        int visited[] = new int[number_of_nodes + 1];   
        visited[0]=1;
        int element = source;       
        int i = source;
        int cc=1;
          for (int k = 1; k <= number_of_nodes; k++){
             if (visited[k] == 0) 
            {
         visited[source] = 1;       
        stack.push(source);        
        while (!stack.isEmpty())
        {
            element = stack.peek();
            i = element;    
        while (i <= number_of_nodes)
        {
                if (adjacency_matrix[element][i] == 1 && visited[i] == 0)
            {
                    stack.push(i);
                    visited[i] = 1;
                    element = i;
                    i = 1;
                continue;
                }
                i++;
        }
            stack.pop();    
        }
        boolean connected = false;

        for (int vertex = 1; vertex <= number_of_nodes; vertex++)
        {
            if (visited[vertex] == 1) 
            {
                connected = true;
            } else
            {
                connected = false;
                            }
        }

           }else
        {
            System.out.print("There are ");
            System.out.print(cc);
            System.out.println(" connected compoments");
        }
}
}

    public static void main(String...arg)
    {
        int number_of_nodes, source;
        Scanner scanner = null;
    try
        {
        System.out.println("Enter the number of nodes in the graph");
            scanner = new Scanner(System.in);
            number_of_nodes = scanner.nextInt();

        int adjacency_matrix[][] = new int[number_of_nodes + 1][number_of_nodes + 1];
        System.out.println("Enter the adjacency matrix");
        for (int i = 1; i <= number_of_nodes; i++)
           for (int j = 1; j <= number_of_nodes; j++)
                   adjacency_matrix[i][j] = scanner.nextInt();

        for (int i = 1; i <= number_of_nodes; i++)
            {
                for (int j = 1; j <= number_of_nodes; j++)
                {   
                     if (adjacency_matrix[i][j] == 1 && adjacency_matrix[j][i] == 0)
                     {
                         adjacency_matrix[j][i] = 1;
                     }
                }
            }           

        System.out.println("Enter the source for the graph");
            source = scanner.nextInt(); 

            UndirectedConnectivityDfs undirectedConnectivity= new UndirectedConnectivityDfs();
            undirectedConnectivity.dfs(adjacency_matrix, source);   

        }catch(InputMismatchException inputMismatch)
        {
            System.out.println("Wrong Input format");
        }   
        scanner.close();    
    }   
}

Answer 1

您的解决方案即将完成。 您必须将变量的范围调整为检查visited数组的for循环内。 另外，您还必须使用从0开始的索引，因为u可能导致ArrayIndexOutOfBoundsException 。 另外，您不必提供源作为输入。 这是固定代码：

public class UndirectedConnectivityDfs
{
    private Stack<Integer> stack;
    public UndirectedConnectivityDfs() 
    {
            stack = new Stack<Integer>();
    } 

    public void dfs(int adjacency_matrix[][])
    {
        int number_of_nodes = adjacency_matrix[0].length;   
        int visited[] = new int[number_of_nodes];       
        int cc = 0;
        for  (int vertex = 0; vertex < number_of_nodes; vertex++)
        {
            if (visited[vertex] == 0)
            {   
                int element = vertex;               
                int i = vertex;     
                visited[vertex] = 1;
                cc++;
                stack.push(vertex);
                while (!stack.isEmpty())
                {
                    element = stack.peek();
                    i = element;    
                    while (i < number_of_nodes)
                    {
                        if (adjacency_matrix[element][i] == 1 && visited[i] == 0)
                        {
                            stack.push(i);
                            visited[i] = 1;
                            element = i;
                            i = 1;
                            continue;
                            }
                            i++;
                    }
                    stack.pop();    
                }
            }
        }
        System.out.println("Number of Connected Components: " + cc);
    }

    public static void main(String...arg)
    {
        int number_of_nodes;
        Scanner scanner = null;
        try
        {
            System.out.println("Enter the number of nodes in the graph");
            scanner = new Scanner(System.in);

            number_of_nodes = scanner.nextInt();
            int adjacency_matrix[][] = new int[number_of_nodes][number_of_nodes];

            System.out.println("Enter the adjacency matrix");

            for (int i = 0; i < number_of_nodes; i++)
                for (int j = 0; j < number_of_nodes; j++)
                       adjacency_matrix[i][j] = scanner.nextInt();

            for (int i = 0; i < number_of_nodes; i++)
            {
                for (int j = 0; j < number_of_nodes; j++)
                {   
                    if (adjacency_matrix[i][j] == 1 && adjacency_matrix[j][i] == 0)
                    {
                            adjacency_matrix[j][i] = 1;
                    }
                    }
            }           
            UndirectedConnectivityDfs undirectedConnectivity= new UndirectedConnectivityDfs();
            undirectedConnectivity.dfs(adjacency_matrix);   

        }catch(InputMismatchException inputMismatch)
        {
            System.out.println("Wrong Input format");
        }   
        scanner.close();    
    }   
}