题解 | 活动安排

import java.util.Scanner;
import java.util.*;
// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNextInt()) { // 注意 while 处理多个 case
            int n = in.nextInt();
            int[][] startEnd = new int[n][2];
            int[] end = new int[n];
            for (int i = 0; i < n; i++) {
                startEnd[i][0] = in.nextInt();
                startEnd[i][1] = in.nextInt();

            }
            Arrays.sort(startEnd, Comparator.comparingInt(o -> o[1]));
            
        int res = 1;
        int result = startEnd[0][1];

        for (int i=1;i<n;i++) {
            if ( startEnd[i][0] >= result) {
                res++;
                result = startEnd[i][1];
            }
        }
           System.out.println(res);
        }
    }
}