import java.util.ArrayList; public class Solution { public ArrayList generateNumbers(int n) { ArrayList ret = new ArrayList(); if (n > 10) { return ret; } Integer[] password = new Integer[n]; solve(ret, password, n, 0); return ret; } public void solve(ArrayList ret, Integer[] password, int n, int index) { if (index == n) { ret.add(password.clone()); } else { for (int i = 0; i 0 && password[index - 1] >= value) { return false; } return true; } }