Java 解法, 执行用时: 7ms, 内存消耗: 8980KB, 提交时间: 2022-02-10

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

        //write your code here........
        String a = "9";
        long sum = 0;
        for(int i = 0; i < 10; i++){
            sum = Long.parseLong(a) + sum;
            a = a + "9";
        }
        System.out.println(sum);
    }
}

Java 解法, 执行用时: 7ms, 内存消耗: 9012KB, 提交时间: 2022-02-10

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

        //write your code here........
       long i = 9;
        long sum = 0;
        while (i<=9999999999L){
            sum = sum + i;
            i = Long.parseLong(String.valueOf(i) + 9);
        }
        System.out.println(sum);

    }
}

Java 解法, 执行用时: 7ms, 内存消耗: 9052KB, 提交时间: 2022-02-09

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

        //write your code here........
        long sum=0;
        long num=0;
        for(int i=0; i<10; i++){
            num+=9*(long)(Math.pow(10,i));
            sum+=num;
        }
        System.out.println(sum);

    }
}

Java 解法, 执行用时: 7ms, 内存消耗: 9080KB, 提交时间: 2021-10-23

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

        //write your code here........
        long var = 0 , sum = 0;
        for(int i = 0 ; i < 10 ; i++){
            var  = var * 10 + 9 ;
            sum += var;
        }
        System.out.print(sum);
    }
}

Java 解法, 执行用时: 7ms, 内存消耗: 9088KB, 提交时间: 2022-02-08

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

        long num = 0,sum = 0;
        
        for(int i =0;i<10;i++){
            num =num*10+9;
            sum +=num;
        }
        System.out.println(sum);
        

    }
}