并查集 推荐使用 1176 ms

import java.io.*;
import java.util.*;

class Main {

    static int idx, n, k;
    static int[] p = new int[1010];
    static int[] w = new int[1010];
    static int[] cnt = new int[1010];
    static boolean[] flag = new boolean[1010];

    //并查集初始化
    static {
        for (int i = 0; i < 1010; i++) {
            p[i] = i;
            cnt[i] = 1;
        }
    }

    static int find(int x) {
        if (p[x] != x) p[x] = find(p[x]);
        return p[x];
    }

    static Map<String, Integer> n2i = new HashMap<>();
    static Map<Integer, String> i2n = new HashMap<>();

    public static void main(String[] args) throws IOException {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader in = new BufferedReader(isr);
        OutputStreamWriter osw = new OutputStreamWriter(System.out);
        BufferedWriter out = new BufferedWriter(osw);
        String[] strs = in.readLine().split(" ");
        n = Integer.parseInt(strs[0]);
        k = Integer.parseInt(strs[1]);

        for (int i = 0; i < n; i++) {
            strs = in.readLine().split(" ");
            String s = strs[0];
            String e = strs[1];
            int v = Integer.parseInt(strs[2]);
            if (!n2i.containsKey(s)) {
                n2i.put(s, idx);
                i2n.put(idx++, s);
            }
            if (!n2i.containsKey(e)) {
                n2i.put(e, idx);
                i2n.put(idx++, e);
            }
            int si = n2i.get(s);
            int ei = n2i.get(e);
            w[si] += v;
            w[ei] += v;
            int fs = find(si);
            int fe = find(ei);
            if (fs != fe) {
                p[fs] = fe;
                cnt[fe] += cnt[fs];
            }
        }

        //记录组织头领姓名
        List<String> leaderNames = new ArrayList<>();
        //遍历每个组织
        for (int i = 0; i < idx; i++) {
            int father = find(i);
            if (cnt[father] < 3 || flag[i]) continue;
            flag[i] = true;
            int maxW = w[i];
            int sum = w[i];
            int maxId = i;
            for (int j = 0; j < idx; j++) {
                if (flag[j] || find(j) != father) continue;
                flag[j] = true;
                sum += w[j];
                if (maxW < w[j]) {
                    maxW = w[j];
                    maxId = j;
                }
            }
            sum /= 2;
            if (sum > k) leaderNames.add(i2n.get(maxId));
        }
        int gNum = leaderNames.size();
        Collections.sort(leaderNames);
        out.write(gNum + "\n");
        for (String name : leaderNames)
            out.write(name + " " + cnt[find(n2i.get(name))] + "\n");

        in.close();
        isr.close();
        out.flush();
        out.close();
        osw.close();
    }
}

DFS 难写、难以debug，不推荐 1186 ms

import java.io.*;
import java.util.*;

class Main {

    static int idx, hidx, n, k;
    //稀疏图，邻接表存储
    static int[] h = new int[1021];
    static int[] e = new int[2021];
    static int[] ne = new int[2021];

    static {
        Arrays.fill(h, -1);
    }

    //每个点的总权重
    static int[] wi = new int[1021];
    //标记是否已访问此点
    static boolean[] flag = new boolean[1021];
    //组织的总权重和最大成员权重
    static int sum, maxW, maxId;
    //存储组织成员数
    static Map<String, Integer> gN = new HashMap<>();

    static Map<String, Integer> n2i = new HashMap<>();
    static Map<Integer, String> i2n = new HashMap<>();

    static void insert(String start, String end, int v) {
        if (!n2i.containsKey(start)) n2i.put(start, idx++);
        if (!n2i.containsKey(end)) n2i.put(end, idx++);
        int si = n2i.get(start);
        int ei = n2i.get(end);
        i2n.put(si, start);
        i2n.put(ei, end);

        e[hidx] = ei;
        ne[hidx] = h[si];
        h[si] = hidx++;
        e[hidx] = si;
        ne[hidx] = h[ei];
        h[ei] = hidx++;

        wi[si] += v;
        wi[ei] += v;
    }

    //返回此组织的成员数量
    static int dfs(int x) {
        flag[x] = true;
        if (wi[x] > maxW) {
            maxW = wi[x];
            maxId = x;
        }
        sum += wi[x];
        int mem = 1;
        for (int i = h[x]; i != -1; i = ne[i]) {
            int nx = e[i];
            if (!flag[nx]) {
                mem += dfs(nx);
            }
        }
        return mem;
    }

    public static void main(String[] args) throws IOException {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader in = new BufferedReader(isr);
        OutputStreamWriter osw = new OutputStreamWriter(System.out);
        BufferedWriter out = new BufferedWriter(osw);
        String[] strs = in.readLine().split(" ");
        n = Integer.parseInt(strs[0]);
        k = Integer.parseInt(strs[1]);

        for (int i = 0; i < n; i++) {
            strs = in.readLine().split(" ");
            String s = strs[0];
            String e = strs[1];
            int v = Integer.parseInt(strs[2]);
            insert(s, e, v);
        }

        //记录组织头领姓名
        List<String> leaderNames = new ArrayList<>();

        int members = 0, gNum = 0;
        for (int i = 0; i < idx; i++) {
            if (!flag[i]) {
                sum = 0;
                maxW = -1;
                members = dfs(i);
                sum /= 2;
                if (members > 2 && sum > k) {
                    gNum++;
                    String name = i2n.get(maxId);
                    leaderNames.add(name);
                    gN.put(name, members);
                }
            }
        }

        out.write(gNum + "\n");
        Collections.sort(leaderNames);
        for (String name : leaderNames) {
            int mem = gN.get(name);
            out.write(name + " " + mem + "\n");
        }

        in.close();
        isr.close();
        out.flush();
        out.close();
        osw.close();
    }

}