题解 | #进制转换#

import java.util.Scanner;
import java.math.BigInteger;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextBigInteger()) { // 注意 while 处理多个 case
            BigInteger n = in.nextBigInteger();
            if(n.equals(BigInteger.valueOf(0))){
                System.out.println(0);
                continue;
            }
            String res = "";
            while(!n.equals(BigInteger.valueOf(0))){
                //取模+除法
                BigInteger temp = n.divideAndRemainder(new BigInteger("2"))[1];
                res+=temp.toString();
                //n进行除法
                n = n.divide(new BigInteger("2"));
            }
            //倒序输出字符串
            StringBuffer sb = new StringBuffer(res);
            System.out.println(sb.reverse());
        }
    }
}