hdu 4577 X-Boxes（大数）

想用c++来写大数，看来还是不太现实，借鉴了java版的

import java.io.*;
import java.math.*;
import java.util.*;
/*
 * (2x-1)*2^(ky-1) <= n 
 * (2x-1)*2^(ky) <= n*2
 */
public class Main
{
    public static void main(String args[])
    {
        Scanner cin = new Scanner(new BufferedInputStream(System.in));
        int t,k;
        BigInteger n,y,c;
        t = cin.nextInt();
        while (t-->0)
        {
            BigInteger res = BigInteger.ZERO;
            n = cin.nextBigInteger();
            k = cin.nextInt();
            n = n.multiply(BigInteger.valueOf(2));
            y = BigInteger.valueOf(1<<k);
            while (n.compareTo(BigInteger.ZERO) > 0)
            {
                n = n.divide(y);
                c = n.add(BigInteger.ONE).divide(BigInteger.valueOf(2));
                res = res.add(c);
            }
            System.out.println(res);
        }
    }
}