计算各个位数不同的数字个数

Author: mayuanucas

src/main/java/algorithm/leetcode/Solution357.java

@@ -15,7 +15,9 @@ public int countNumbersWithUniqueDigits(int n) {
 
  for (int i = 3, num = 8; i < f.length; ++i) {
  f[i] = f[i - 1] * num;
- --num;
+ if (1 < num) {
+ --num;
+ }
  }
  for (int i = 2; i < f.length; ++i) {
  f[i] += f[i - 1];