import java.util.Arrays; import java.util.Comparator; import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner sc = new Scanner(System.in); while (sc.hasNext()) { int n = sc.nextInt(); int[][] toys = new int[n][2]; for (int i = 0; i < n; i++) { toys[i][0] = sc.nextInt(); toys[i][1] = sc.nextInt(); } Arrays.sort(toys, new Comparator<int[]>() { @Override public int compare(int[] o1, int[] o2) { if (o1[0] == o2[0]) return o1[1] <= o2[1] ? -1 : 1; return o1[0] <= o2[0] ? -1 : 1; } }); int count = 1; int i = 0, j = 1; while (j <= n-1) { if (toys[j][0] > toys[i][0] && toys[j][1] > toys[i][1]) { count++; i = j; } j++; } System.out.println(count); } } } 为什么感觉我写的好low，虽然AC了。。