240831 단어 섞기

public static void main(String[] args) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	StringBuilder sb = new StringBuilder();
	int t = Integer.parseInt(br.readLine());

	for (int tc = 1; tc <= t; ++tc) {
		StringTokenizer st = new StringTokenizer(br.readLine());
		String line1 = st.nextToken();
		String line2 = st.nextToken();
		String line3 = st.nextToken();
		sb.append("Data set ").append(tc).append(": ")
				.append(isInterleaving(line1, line2, line3) ? "yes\n" : "no\n");
	}

	System.out.print(sb);
}

private static boolean isInterleaving(String line1, String line2, String line3) {
	int[] charCount = new int[256];
	int n = line1.length();
	int m = line2.length();
	int l = line3.length();

	if (n + m != l)
		return false;

	for (char c : line1.toCharArray())
		charCount[c]++;
	for (char c : line2.toCharArray())
		charCount[c]++;
	for (char c : line3.toCharArray())
		charCount[c]--;

	for (int count : charCount) {
		if (count != 0)
			return false;
	}

	return isSubsequence(line1, line3) && isSubsequence(line2, line3);
}

private static boolean isSubsequence(String s1, String s2) {
	int idx = 0;
	for (char c : s2.toCharArray()) {
		if (idx < s1.length() && c == s1.charAt(idx)) {
			idx++;
		}
	}
	return idx == s1.length();
}

출처:https://www.acmicpc.net/problem/9177