题解 | #规律数列求和#

#include <iostream>
using namespace std;

int main() {

    // write your code here......
    int i;//控制次数

    long long int t = 1;
    int j;
    long long int sum = 0;
    for (i = 1; i <=10; i++)
    {
       
        
            t = t * 10;
            
            sum = sum + t - 1;
        
        
        
    }

    cout << sum;
    
    return 0;
}