Java | Leetcode Java题解之第357题统计各位数字都不同的数字个数

题目：

题解：

class Solution {public int countNumbersWithUniqueDigits(int n) {if (n == 0) {return 1;}if (n == 1) {return 10;}int res = 10, cur = 9;for (int i = 0; i < n - 1; i++) {cur *= 9 - i;res += cur;}return res;}
}