java如何實(shí)現(xiàn)拓?fù)鋱D

小億
96
2024-09-13 15:16:04

在Java中，實(shí)現(xiàn)拓?fù)鋱D可以通過(guò)使用鄰接表或鄰接矩陣來(lái)表示圖。這里我將給出一個(gè)使用鄰接表實(shí)現(xiàn)的簡(jiǎn)單示例。拓?fù)鋱D是有向無(wú)環(huán)圖（Directed Acyclic Graph，簡(jiǎn)稱DAG）的一種應(yīng)用場(chǎng)景。

首先，我們需要?jiǎng)?chuàng)建一個(gè)表示圖的類，包括頂點(diǎn)和邊。然后，我們可以使用深度優(yōu)先搜索（DFS）或廣度優(yōu)先搜索（BFS）來(lái)遍歷圖并實(shí)現(xiàn)拓?fù)渑判颉?/p>

以下是一個(gè)簡(jiǎn)單的實(shí)現(xiàn)：

  1. 定義頂點(diǎn)類（Vertex）：
public class Vertex {
    private String label;
    private List<Vertex> neighbors;

    public Vertex(String label) {
        this.label = label;
        this.neighbors = new ArrayList<>();
    }

    public void addNeighbor(Vertex neighbor) {
        this.neighbors.add(neighbor);
    }

    public String getLabel() {
        return label;
    }

    public List<Vertex> getNeighbors() {
        return neighbors;
    }
}
  1. 定義圖類（Graph）：
public class Graph {
    private List<Vertex> vertices;

    public Graph() {
        this.vertices = new ArrayList<>();
    }

    public void addVertex(Vertex vertex) {
        this.vertices.add(vertex);
    }

    public List<Vertex> getVertices() {
        return vertices;
    }
}
  1. 實(shí)現(xiàn)拓?fù)渑判颍═opological Sort）：
public class TopologicalSort {
    public static List<Vertex> topologicalSort(Graph graph) {
        List<Vertex> sortedVertices = new ArrayList<>();
        Set<Vertex> visitedVertices = new HashSet<>();

        for (Vertex vertex : graph.getVertices()) {
            if (!visitedVertices.contains(vertex)) {
                dfs(vertex, visitedVertices, sortedVertices);
            }
        }

        Collections.reverse(sortedVertices);
        return sortedVertices;
    }

    private static void dfs(Vertex currentVertex, Set<Vertex> visitedVertices, List<Vertex> sortedVertices) {
        visitedVertices.add(currentVertex);

        for (Vertex neighbor : currentVertex.getNeighbors()) {
            if (!visitedVertices.contains(neighbor)) {
                dfs(neighbor, visitedVertices, sortedVertices);
            }
        }

        sortedVertices.add(currentVertex);
    }
}
  1. 測(cè)試拓?fù)渑判颍?/li> 
public class Main {
    public static void main(String[] args) {
        Graph graph = new Graph();

        Vertex v1 = new Vertex("1");
        Vertex v2 = new Vertex("2");
        Vertex v3 = new Vertex("3");
        Vertex v4 = new Vertex("4");
        Vertex v5 = new Vertex("5");

        graph.addVertex(v1);
        graph.addVertex(v2);
        graph.addVertex(v3);
        graph.addVertex(v4);
        graph.addVertex(v5);

        v1.addNeighbor(v2);
        v1.addNeighbor(v3);
        v2.addNeighbor(v4);
        v3.addNeighbor(v4);
        v4.addNeighbor(v5);

        List<Vertex> sortedVertices = TopologicalSort.topologicalSort(graph);

        for (Vertex vertex : sortedVertices) {
            System.out.print(vertex.getLabel() + " ");
        }
    }
}

輸出結(jié)果：

1 3 2 4 5

這個(gè)示例展示了如何在Java中實(shí)現(xiàn)拓?fù)鋱D。你可以根據(jù)自己的需求對(duì)這個(gè)實(shí)現(xiàn)進(jìn)行擴(kuò)展和修改。

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