招商银行信用卡中心研发岗笔试第三题求解

在N个数中找出好数个数，我直接用的穷举法，但测试用例只通过了57%（并没报超过时间限制）。有人ac100%的吗？求解题思路

using namespace std;
 int isnotX(int a) {
 int temp = 0;
 if (a % 10 == 2 || a % 10 == 5 || a % 10 == 6 || a % 10 == 9 || a % 10 == 0 || a % 10 == 1 || a % 10 == 8)
 temp = 0;
 else
 temp = 1;
 if ((a / 10) == 0)
 return temp;
 else
 return temp + isnotX(a / 10);
 }
 bool isbug(int a) {
 while (true) {
 if (a % 10 == 0 || a % 10 == 1 || a % 10 == 8) {
 if (a / 10 == 0)
 return 1;
 else
 a = a / 10;
 }
 else
 return 0;
 }
}
 int main() {
 int N;
 cin >> N;
 int count = 0;
 for (int i = 0; i < N; i++) {
 if ((isnotX(i) == 0) && (isbug(i) == 0))
 {
 //cout << i << " ";
 count++;
 }
}
 cout << count;
 system("pause");
 }