java kruskal算法代码实现

Kruskal算法是一种最小生成树的算法，它以边为基础来构建最小生成树。下面是Java语言实现Kruskal算法的代码示例：

import java.util.*;

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

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

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

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

        int parent[] = new int[V];

        Arrays.fill(parent, -1);

        i = 0;

        while (e < V - 1) {
            Edge next_edge = new Edge();
            next_edge = edge[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 KruskalAlgorithm {
    public static void main(String[] args) {
        int V = 4;
        int E = 5;
        Graph graph = new Graph(V, E);

        graph.edge[0].src = 0;
        graph.edge[0].dest = 1;
        graph.edge[0].weight = 10;

        graph.edge[1].src = 0;
        graph.edge[1].dest = 2;
        graph.edge[1].weight = 6;

        graph.edge[2].src = 0;
        graph.edge[2].dest = 3;
        graph.edge[2].weight = 5;

        graph.edge[3].src = 1;
        graph.edge[3].dest = 3;
        graph.edge[3].weight = 15;

        graph.edge[4].src = 2;
        graph.edge[4].dest = 3;
        graph.edge[4].weight = 4;

        graph.KruskalMST();
    }
}

以上代码实现了Kruskal算法，并输出了最小生成树的边和权重。注意，这里的实现是使用了并查集来维护已经添加到生成树中的节点。