Leetcode 357. Count Numbers with Unique Digits

class Solution {
public:
    int countNumbersWithUniqueDigits(int n) {
        int total = 1;
        for(int i = 0; i < n; i++) {
            int count = 9;
            for(int j = 1; j <= i; j++) {
                count *= (10 - j);
            }
            total += count;
        }
        return total;
    }
};