最长上升子序列O(n^2) java

import java.util.Arrays;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 arr[] = new int[n];int f[] = new int[n];f[0] = 1;int ans = 0;for (int i = arr.length - 1; i >= 0; i--) {arr[i] = sc.nextInt();}for (int i = 0; i < arr.length; i++) {int m = 0;for (int j = 0; j < i; j++) {if (f[j] > m && arr[j] <= arr[i]) {m = f[j];}}f[i] = m + 1;if (ans < f[i]) {ans = f[i];}}System.out.println(ans);}}}