并查集模版（Java）

并查集模版（Java）

import java.util.Scanner;

public class UnionFind {

    public static int[] parent;

    //获得该集合的老大，带路径压缩
    public static int get_boss(int v) {
        if (parent[v] == v)
            return v;
        else {
            parent[v] = get_boss(parent[v]);
            return parent[v];
        }
    }

    //合并两个集合
    public static void Merge(int v, int u) {
        int t1 = get_boss(v);
        int t2 = get_boss(u);
        parent[t2] = t1;
    }


    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();   //n个人
        int m = sc.nextInt();   //m个关系

        parent = new int[n + 1];

        for (int i = 1; i <= n; i++) {
            parent[i] = i;
        }

        for (int i = 0; i < m; i++) {
            int a = sc.nextInt();
            int b = sc.nextInt();
            Merge(a, b);
        }

        int count = 0;
        for (int i = 1; i <= n; i++) {
            if (parent[i] == i) {
                count++;
            }
        }

        System.out.println("团队数量：" + count);
    }

}

朋友圈：https://leetcode-cn.com/problems/friend-circles/

public class P547FriendCircles {
    /**
     * [[1,1,0],
     * [1,1,0],
     * [0,0,1]]
     * 输出: 2
     */
    public static void main(String[] args) {
        Solution solution = new P547FriendCircles().new Solution();
        // TO TEST
        System.out.println(solution.findCircleNum(new int[][]{{1, 1, 0}, {1, 1, 0}, {0, 0, 1}}));
    }

    //leetcode submit region begin(Prohibit modification and deletion)
    class Solution {
        int[] parent = new int[200];

        public int findCircleNum(int[][] M) {

            int rows = M.length;


            for (int i = 0; i < 200; i++) {
                parent[i] = i;
            }


            for (int i = 0; i < rows; i++) {
                for (int j = i + 1; j < rows; j++) {
                    if (M[i][j] == 1) {
                        merge(i, j);
                    }
                }
            }

            int count = 0;
            for (int i = 0; i < rows; i++) {
                if (parent[i] == i) {
                    count++;
                }
            }
            return count;
        }

        private int getParent(int x) {
            return parent[x] == x ? x : getParent(parent[x]);
        }

        private void merge(int x, int y) {
            int px = getParent(x);
            int py = getParent(y);
            parent[py] = px;
        }
    }
}