二维的最长递增子序列问题。

package Solution;

public class Solution
{
    private class score implements Comparable<Object>
    {
        public int sat;
        public int gpa;
        public int compareTo(Object obj)
        {
            score o = (score) obj;
            return gpa != o.gpa ? o.gpa - gpa : sat - o.sat;
        }
        public score(int _sat, int _gpa)
        {
            sat = _sat;
            gpa = _gpa;
        }
    }

    private score[] scores;
    private score[] scoreOfLength;
    
    private void input()
    {
        java.util.Scanner scanner = new java.util.Scanner(System.in);
        int N = scanner.nextInt();
        scores = new score[N];
        scoreOfLength = new score[N + 1];
        for (int i = 0; i < N; ++i)
        {
            int sat = scanner.nextInt();
            int gpa = scanner.nextInt();
            scores[i] = new score(sat, gpa);
        }
        scanner.close();
    }
    private int lower_bound(int x)
    {
        int p = 1;
        int q = scoreOfLength.length - 1;
        while(true)
        {
            int m = p + (q - p) / 2;
            if(scoreOfLength[m].sat >= x && scoreOfLength[m - 1].sat < x)
            {
                return m;
            }
            if(scoreOfLength[m].sat < x)
            {
                p = m + 1;
            }
            else
            {
                q = m - 1;
            }
        }
    }
    
    public int solve()
    {
        input();
        java.util.Arrays.sort(scores);
        scoreOfLength[0] = new score(Integer.MIN_VALUE, -1);
        for(int i = 1; i < scoreOfLength.length; ++i)
        {
            scoreOfLength[i] = new score(Integer.MAX_VALUE, -1);
        }
        int ans = 0;
        for(int i = 0; i < scores.length; ++i)
        {
            int k = lower_bound(scores[i].sat);
            if(scores[i].gpa != scoreOfLength[k - 1].gpa)
            {
                scoreOfLength[k] = scores[i];
                if(k > ans)
                {
                    ans = k;
                }
            }
        }
        return ans;
    }

    public static void main(String[] args)
    {
        Solution s = new Solution();
        System.out.println(s.solve());
    }
}