int countNumbersWithUniqueDigits(int n) {
if(n > 10){
return countNumbersWithUniqueDigits(10);
}
maxNum = pow(10,n);
bool used[10];
int count = 1;
for (int i=1; i<10; i++){
used[i] = true;
count += search(i, used);
used[i] = false;
}
return count;
}
int countNumbersWithUniqueDigits(int n) {
if (n == 0) return 1;
int count = 9;
for (int i = 0, digit = 9; i != n - 1; ++i, --digit) count *= digit;
return count + countNumbersWithUniqueDigits(n - 1);
}
