使用Java ArrayList 的图形表示

先决条件：图形及其表示

在本文中，我们将讨论在Java使用 ArrayList 的 Graph 邻接列表表示。

以下是上图的邻接表表示。

这个想法是使用ArrayLists的ArrayList。

// Java code to demonstrate Graph representation
// using ArrayList in Java
import java.util.*;
  
class Test {
  
    static void addEdge(ArrayList > adj,
                        int u, int v)
    {
        adj.get(u).add(v);
        adj.get(v).add(u);
    }
  
    static void printAdjacencyList(ArrayList > adj)
    {
        for (int i = 0; i < adj.size(); i++) {
            System.out.println("Adjacency list of " + i);
            for (int j = 0; j < adj.get(i).size(); j++) {
                System.out.print(adj.get(i).get(j) + " ");
            }
            System.out.println();
        }
    }
  
    public static void main(String[] args)
    {
        // Creating a graph with 5 vertices
        int V = 5;
        ArrayList > adj = new ArrayList >(V);
        for (int i = 0; i < V; i++)
            adj.add(new ArrayList());
  
        // Adding edges one by one.
        addEdge(adj, 0, 1);
        addEdge(adj, 0, 4);
        addEdge(adj, 1, 2);
        addEdge(adj, 1, 3);
        addEdge(adj, 1, 4);
        addEdge(adj, 2, 3);
        addEdge(adj, 3, 4);
        printAdjacencyList(adj);
    }
}

输出：

Adjacency list of 0
1 4 
Adjacency list of 1
0 2 3 4 
Adjacency list of 2
1 3 
Adjacency list of 3
1 2 4 
Adjacency list of 4
0 1 3

使用单独的图形类的类似实现。

// Java code to demonstrate Graph representation
// using ArrayList in Java
import java.util.*;
  
class Graph {
    ArrayList > adj;
    int V;
    Graph(int v)
    {
        V = v;
        adj = new ArrayList >(V);
        for (int i = 0; i < V; i++)
            adj.add(new ArrayList());
    }
  
    void addEdge(int u, int v)
    {
        adj.get(u).add(v);
        adj.get(v).add(u);
    }
  
    void printAdjacencyList()
    {
        for (int i = 0; i < adj.size(); i++) {
            System.out.println("Adjacency list of " + i);
            for (int j = 0; j < adj.get(i).size(); j++) {
                System.out.print(adj.get(i).get(j) + " ");
            }
            System.out.println();
        }
    }
}
  
class Test {
  
    public static void main(String[] args)
    {
        // Creating a graph with 5 vertices
        int V = 5;
  
        Graph g = new Graph(V);
  
        // Adding edges one by one.
        g.addEdge(0, 1);
        g.addEdge(0, 4);
        g.addEdge(1, 2);
        g.addEdge(1, 3);
        g.addEdge(1, 4);
        g.addEdge(2, 3);
        g.addEdge(3, 4);
        g.printAdjacencyList();
    }
}

输出：

Adjacency list of 0
1 4 
Adjacency list of 1
0 2 3 4 
Adjacency list of 2
1 3 
Adjacency list of 3
1 2 4 
Adjacency list of 4
0 1 3

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