杭電 2031 ( 進制轉換 ) java

import java.util.*;
public class Main {
    public static void main(String args[]){
        Scanner cin=new Scanner(System.in);
        while(cin.hasNext()){
            int n=cin.nextInt();//十進制數n
            int r=cin.nextInt();//R進制數r
            String s="";
            if(n<0){
                n=-n;
                System.out.print("-");
            }
            char a='A';
            int b=a;
            while(n>0){
                int t=n%r;                
                if(t>=10){
                    int c=t-10+b;
                    char d=(char)c;
                    s=s+d;                                
                }
                else
                    s=s+t;
                    n=n/r;
            }
            StringBuffer str=new StringBuffer(s);
            s=str.reverse().toString();
            System.out.println(str);
        }
    }
}