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);
         }
     }
 }