Java實現Kruskal演演算法的範例程式碼

package graph.kruskal;
 
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;
 
public class Kruskal {
    static final int N = 100;
    static int fa[] = new int[N];
    static int n;
    static int m;
 
    static Edge e[] = new Edge[N * N];
    static List<Edge> edgeList = new ArrayList();
 
    static {
        for (int i = 0; i < e.length; i++) {
            e[i] = new Edge();
        }
    }
 
    // 初始化集合號為自身
    static void Init(int n) {
        for (int i = 1; i <= n; i++)
            fa[i] = i;
    }
 
    // 合併
    static int Merge(int a, int b) {
        int p = fa[a];
        int q = fa[b];
        if (p == q) return 0;
        for (int i = 1; i <= n; i++) { // 檢查所有結點，把集合號是 q 的改為 p
            if (fa[i] == q)
                fa[i] = p; // a 的集合號賦值給 b 集合號
        }
        return 1;
    }
 
    // 求最小生成樹
    static int Kruskal(int n) {
        int ans = 0;
        Collections.sort(edgeList);
        for (int i = 0; i < m; i++)
            if (Merge(edgeList.get(i).u, edgeList.get(i).v) == 1) {
                ans += edgeList.get(i).w;
                n--;
                if (n == 1)//n-1次合併演演算法結束
                    return ans;
            }
        return 0;
    }
 
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        n = scanner.nextInt();
        m = scanner.nextInt();
        Init(n);
        for (int i = 1; i <= m; i++) {
            e[i].u = scanner.nextInt();
            e[i].v = scanner.nextInt();
            e[i].w = scanner.nextInt();
            edgeList.add(e[i]);
        }
        System.out.println("最小的花費是：" + Kruskal(n));
    }
}
 
class Edge implements Comparable {
    int u;
    int w;
    int v;
 
    @Override
    public int compareTo(Object o) {
        if (this.w > ((Edge) o).w) {
            return 1;
        } else if (this.w == ((Edge) o).w) {
            return 0;
        } else {
            return -1;
        }
    }
}