杭电2132An easy problem

原题链接

import java.util.*;import java.math.*;public class Main {    public static void main(String[] args) {        Scanner cin=new Scanner(System.in);        BigInteger a[]=new BigInteger [100003];       a[0]=BigInteger.valueOf(0);                for(int i=1;i<=100001;i++) {                    BigInteger t=BigInteger.valueOf(i);                    if(i%3==0)                        a[i]=a[i-1].add(t.multiply(t).multiply(t));                    else                        a[i]=a[i-1].add(t);                }                while(cin.hasNext()) {                    int n=cin.nextInt();                    if(n<0)                        break;                    else                        System.out.println(a[n]);                       }    }}