克鲁斯卡尔算法java

克鲁斯卡尔算法是一种用于求解最小生成树的算法，它的基本思路是将所有的边按照权值从小到大排序，然后依次选择权值最小的边，如果该边的两个端点不在同一个连通分量中，则将它们合并到同一个连通分量中，直到所有的点都在同一个连通分量中，此时就得到了最小生成树。

以下是克鲁斯卡尔算法的Java实现：

import java.util.Arrays;

class Edge implements Comparable<Edge> {
    int src, dest, weight;

    public int compareTo(Edge edge) {
        return this.weight - edge.weight;
    }
};

class Graph {
    int V, E;
    Edge[] edges;

    Graph(int v, int e) {
        V = v;
        E = e;
        edges = new Edge[E];
        for (int i = 0; i < E; ++i) {
            edges[i] = new Edge();
        }
    }

    int find(int[] parent, int i) {
        if (parent[i] == -1) {
            return i;
        }
        return find(parent, parent[i]);
    }

    void union(int[] parent, int x, int y) {
        int xset = find(parent, x);
        int yset = find(parent, y);
        parent[xset] = yset;
    }

    void kruskalMST() {
        Edge[] result = new Edge[V];
        int e = 0;
        int i = 0;
        for (i = 0; i < V; ++i) {
            result[i] = new Edge();
        }

        Arrays.sort(edges);

        int[] parent = new int[V];
        Arrays.fill(parent, -1);

        i = 0;

        while (e < V - 1) {
            Edge next_edge = edges[i++];
            int x = find(parent, next_edge.src);
            int y = find(parent, next_edge.dest);

            if (x != y) {
                result[e++] = next_edge;
                union(parent, x, y);
            }
        }

        System.out.println("Following are the edges in the constructed MST");
        int minimumCost = 0;
        for (i = 0; i < e; ++i) {
            System.out.println(result[i].src + " - " + result[i].dest + ": " + result[i].weight);
            minimumCost += result[i].weight;
        }
        System.out.println("Minimum Cost Spanning Tree: " + minimumCost);
    }
}

public class Main {
    public static void main(String[] args) {
        int V = 4; // Number of vertices in graph
        int E = 5; // Number of edges in graph
        Graph graph = new Graph(V, E);

        // add edge 0-1
        graph.edges[0].src = 0;
        graph.edges[0].dest = 1;
        graph.edges[0].weight = 10;

        // add edge 0-2
        graph.edges[1].src = 0;
        graph.edges[1].dest = 2;
        graph.edges[1].weight = 6;

        // add edge 0-3
        graph.edges[2].src = 0;
        graph.edges[2].dest = 3;
        graph.edges[2].weight = 5;

        // add edge 1-3
        graph.edges[3].src = 1;
        graph.edges[3].dest = 3;
        graph.edges[3].weight = 15;

        // add edge 2-3
        graph.edges[4].src = 2;
        graph.edges[4].dest = 3;
        graph.edges[4].weight = 4;

        graph.kruskalMST();
    }
}

以上代码实现了一个简单的图，包含四个顶点和五条边，可以根据实际情况修改。运行后输出最小生成树的边和总权值。