240914 친구 네트워크

public static void main(String[] args) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
	StringBuilder sb = new StringBuilder();

	int testCaseCount = Integer.parseInt(br.readLine());

	while (testCaseCount-- > 0) {
		Map<String, Integer> nameMapper = new HashMap<>();
		int friendshipCount = Integer.parseInt(br.readLine());
		int[] parent = new int[friendshipCount * 2];
		Arrays.fill(parent, -1);

		while (friendshipCount-- > 0) {
			StringTokenizer st = new StringTokenizer(br.readLine());
			String name1 = st.nextToken();
			String name2 = st.nextToken();

			if (!nameMapper.containsKey(name1)) {
				nameMapper.put(name1, nameMapper.size());
			}
			if (!nameMapper.containsKey(name2)) {
				nameMapper.put(name2, nameMapper.size());
			}

			int friend1 = nameMapper.get(name1);
			int friend2 = nameMapper.get(name2);

			sb.append(union(parent, friend1, friend2)).append("\n");
		}
	}

	bw.write(sb.toString());
	bw.flush();
	bw.close();
	br.close();
}

private static int find(int[] parent, int x) {
	if (parent[x] < 0) {
		return x;
	}
	parent[x] = find(parent, parent[x]);
	return parent[x];
}

private static int union(int[] parent, int a, int b) {
	a = find(parent, a);
	b = find(parent, b);

	if (a != b) {
		parent[a] += parent[b];
		parent[b] = a;
	}
	return -parent[a];
}

출처:https://www.acmicpc.net/problem/4195