题解 | #规律数列求和#

```#include <iostream>
#include <cmath>
using namespace std;

int main() {

    // write your code here......
    long long int sum=0;
	int count=1;
    for(int i=1;i<=10;i++){
        sum+=pow(10,count)-1;
        count++;
    }
    cout<<sum<<endl;
    return 0;
}