Untitled

import java.util.Arrays;

public class RussianDollEnvelopesLIS {
    public int maxEnvelopes(int[][] envelopes) {
        int n = envelopes.length;
        // Step 1: Sort envelopes by width (ascending), and by height (ascending) when widths are equal
        Arrays.sort(envelopes, (a, b) -> a[0] == b[0] ? a[1] - b[1] : a[0] - b[0]);

        // Step 2: dp[i] represents the LIS ending at envelope i
        int[] dp = new int[n];
        Arrays.fill(dp, 1);

        int maxLength = 1;

        // Step 3: Calculate LIS ending at each envelope
        for (int i = 1; i < n; i++) {
            for (int j = 0; j < i; j++) {
                if (envelopes[i][0] > envelopes[j][0] && envelopes[i][1] > envelopes[j][1]) {
                    dp[i] = Math.max(dp[i], dp[j] + 1);
                }
            }
            maxLength = Math.max(maxLength, dp[i]);
        }

        return maxLength;
    }

    public static void main(String[] args) {
        RussianDollEnvelopesLIS rde = new RussianDollEnvelopesLIS();
        System.out.println(rde.maxEnvelopes(new int[][]{{5, 4}, {6, 4}, {6, 7}, {2, 3}})); // Output: 3
        System.out.println(rde.maxEnvelopes(new int[][]{{1, 1}, {1, 1}, {1, 1}}));         // Output: 1
    }
}