public class Solution {
public int CountNumbersWithUniqueDigits(int n) {
if (n == )
{
return ;
}
int res = ;
int uniqueDigits = ;
int availableNumber = ;
while (n-- > && availableNumber > )
{
uniqueDigits = uniqueDigits * availableNumber;
res += uniqueDigits;
availableNumber--;
}
return res;
}
}https://leetcode.com/problems/count-numbers-with-unique-digits/#/description