java数据结构和算法------图(最小生成树Kruskal)

package iYou.neugle.graph;

import java.util.Set;
import java.util.TreeSet;

//创建图过程的代码在图的那篇博文中，此处直接使用
public class Kruskal {
    private MyGraph1 graph;
    private int[] a;// 并查集使用数组(存储前置节点)
    private Set<Edge> edgeSet = new TreeSet<>();// 边的集合按w的升序排序

    class Edge implements Comparable<Object> {
        public int start;// 开始边
        public int end;// 结束边
        public int w;// 权值

        // 将边的集合进行w的升序排序
        @Override
        public int compareTo(Object o) {
            if (o instanceof Edge) {
                Edge edge = (Edge) o;
                if (this.w >= edge.w) {
                    return 1;
                } else {
                    return -1;
                }
            }
            return 0;
        }
    }

    // 并查集
    // 首先初始化各个节点
    private void MakeSet(int n) {
        for (int i = 0; i < n; i++) {
            a[i] = i;
        }
    }

    // 查找根节点
    private int Find(int n) {
        if (a[n] == n) {
            return n;
        } else {
            return Find(a[n]);
        }
    }

    // 合并节点
    private void UnionSet(int x, int y) {
        if (a[x] != a[y]) {
            a[this.Find(y)] = this.Find(x);
        }
    }

    public Kruskal(MyGraph1 graph) {
        this.graph = graph;
        a = new int[this.graph.getGraph().maxNum];
    }

    // 初始化edgeSet集合
    private void Init() {
        // 如果为无向图
        if (this.graph.getGraph().type == 0) {
            for (int i = 0; i < this.graph.getGraph().maxNum; i++) {
                for (int j = 0; j < i; j++) {
                    Function(j, i);
                }
            }
        }
        // 如果为有向图
        else {
            for (int i = 0; i < this.graph.getGraph().maxNum; i++) {
                for (int j = 0; j < this.graph.getGraph().maxNum; j++) {
                    Function(i, j);
                }
            }
        }
    }

    // 功能函数
    private void Function(int i, int j) {
        int w = this.graph.getGraph().edge[i][j];
        if (w != 0) {
            Edge edge = new Edge();
            edge.start = i;
            edge.end = j;
            edge.w = w;
            this.edgeSet.add(edge);
        }
    }

    public void KruskalCore() {
        this.Init();
        int maxNum = this.graph.getGraph().maxNum;
        // 初始化a
        this.MakeSet(maxNum);
        Edge[] edgeArr = this.edgeSet.toArray(new Edge[] {});
        int sum = edgeArr[0].w;
        // 合并一条边的两个节点
        this.UnionSet(edgeArr[0].start, edgeArr[0].end);
        System.out.println("最小生成树为--------");
        System.out
                .println((edgeArr[0].start + 1) + "->" + (edgeArr[0].end + 1));
        // 通过并查集进行判断是否该条边生成回路
        int n = 1;
        for (int i = 1; i < edgeArr.length && n < maxNum; i++) {
            if (this.Find(edgeArr[i].start) != this.Find(edgeArr[i].end)) {
                this.UnionSet(edgeArr[i].start, edgeArr[i].end);
                System.out.println((edgeArr[i].start + 1) + "->"
                        + (edgeArr[i].end + 1));
                sum += edgeArr[i].w;
            }
            n++;
        }
        System.out.println("----------------");
        System.out.println("最小生成树的权值为: " + sum);
    }

    public static void main(String[] args) {
        MyGraph1 graph = new MyGraph1(5, 0);
        graph.CreateMaxtrixGraph(1, 2, 2);
        graph.CreateMaxtrixGraph(1, 3, 5);
        graph.CreateMaxtrixGraph(1, 5, 3);
        graph.CreateMaxtrixGraph(2, 4, 4);
        graph.CreateMaxtrixGraph(3, 5, 5);
        graph.CreateMaxtrixGraph(4, 5, 2);
        graph.OutPutMaxtrixGraph();
        Kruskal kruskal = new Kruskal(graph);
        kruskal.KruskalCore();
    }
}

  1 2 3 4 5 
1 0 2 5 0 3 
2 2 0 0 4 0 
3 5 0 0 0 5 
4 0 4 0 0 2 
5 3 0 5 2 0 
最小生成树为--------
1->2
4->5
1->5
1->3
----------------
最小生成树的权值为: 12