给定a和n,计算a+aa+aaa+a...a(n个a)的和,其中,1<=a<=9,1<=n<=100
其实就是利用BigInteger模拟。
import java.math.BigInteger;
import java.util.Scanner;
public class Main {
public static void main(String[] argc) {
Scanner in=new Scanner(System.in);
while(in.hasNext()) {
int a=in.nextInt();
int n=in.nextInt();
BigInteger sum=BigInteger.valueOf(0);
BigInteger aa=BigInteger.valueOf(a);
BigInteger aaa=aa;
BigInteger radix=BigInteger.valueOf(10);
for(int i=1;i<=n;i++) {
sum=sum.add(aaa);
aaa=aaa.add(aa.multiply(radix.pow(i)));
}
System.out.println(sum);
}
}
}