hdu 4577 X-Boxes 大数

java水过……

代码如下：

import java.math.*;
import java.util.*;
public class Main {
    public static void main(String arg[]){
        BigInteger n,ans,sum;
        Scanner cin = new Scanner(System.in);
        int k,t=cin.nextInt();    
        while(t-->0){
            n=cin.nextBigInteger();
            k=cin.nextInt();
            ans=BigInteger.ZERO;
            while(true){
                n=n.divide(BigInteger.valueOf(1<<(k-1)));
                sum=n.subtract(n.divide(BigInteger.valueOf(2)));
                if(sum.equals(BigInteger.ZERO)) break;
                ans=ans.add(sum);
                n=n.divide(BigInteger.valueOf(2));
            }
            System.out.println(ans);
        }
    }
}