题目地址：https://www.acwing.com/problem/content/15/
AC代码
class Solution {
public:
int NumberOf1Between1AndN_Solution(int n)
{
int count = 0;
for (int i = 1; i <= n; i *= 10) {
int a = n / i,b = n % i;
count += (a + 8) / 10 * i + ((a % 10 == 1) ? b + 1 : 0);
}
return count;
}
};
