题解 | 划分子集就是求最大连通分量的大小

import java.util.Scanner;

public class Main {
    private static int[] parents;

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt(), m = sc.nextInt();
        parents = new int[n + 1];
        int[] counts = new int[n + 1];
        for (int i = 1; i <= n; i++) {
            parents[i] = i;
            counts[i] = 1;
        }
        while (m-- > 0) {
            int u = find(sc.nextInt()), v = find(sc.nextInt());
            if (u != v) {
                parents[v] = u;
                counts[u] += counts[v];
            }
        }
        int ans = 0;
        for (int x : counts) if (x > ans) ans = x;
        System.out.println(ans);
        sc.close();
    }

    private static int find(int x) {
        return parents[x] == x ? x : (parents[x] = find(parents[x]));
    }
}