题解 | #数列求和#

public class Main { public static void main(String[] args) {

    //write your code here........
    long sum = 0L;
    long temp = 0L;
    for(int i = 1;i <= 10;i++){
        //先求数列
        temp = temp * 10 + 9;
        //后求和
        sum = sum + temp;
    }
    System.out.print(sum);
}

}