240830 LCS 2

public static void main(String[] args) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	StringBuilder sb = new StringBuilder();
	char[] str1 = br.readLine().toCharArray();
	char[] str2 = br.readLine().toCharArray();
	int[][] dp = new int[str1.length + 1][str2.length + 1];

	for (int i = 1; i <= str1.length; i++) {
		for (int j = 1; j <= str2.length; j++) {
			if (str1[i - 1] == str2[j - 1]) {
				dp[i][j] = dp[i - 1][j - 1] + 1;
			} else {
				dp[i][j] = Math.max(dp[i - 1][j], dp[i][j - 1]);
			}
		}
	}

	sb.append(dp[str1.length][str2.length]).append("\n");

	Stack<Character> stack = new Stack<>();
	int i = str1.length;
	int j = str2.length;
	while (i > 0 && j > 0) {
		if (dp[i][j] == dp[i - 1][j]) {
			i--;
		} else if (dp[i][j] == dp[i][j - 1]) {
			j--;
		} else {
			stack.push(str1[i - 1]);
			i--;
			j--;
		}
	}

	while (!stack.isEmpty()) {
		sb.append(stack.pop());
	}
	System.out.println(sb);
}

출처:https://www.acmicpc.net/problem/9252