17. 打印从1到最大的n位数¶

输入: n = 1
输出: [1,2,3,4,5,6,7,8,9]

class Solution {
    public int[] printNumbers(int n) {
        int num = 1;
        for(int i = 0;i < n ;i++){
            num *= 10;
        }
        int[] arr = new int[num -1];
        for(int i = 1;i < num;i++){
            arr[i-1] = i;
        }
        return arr;
    }
}