poj1546

进制转换，java做

StringBuffer 的方法中setCharAt(int,char)可以改变其某位的字符

import java.io.*;
import java.util.*;
import java.math.*;

public class Main {
    public static void main(String[] args)
    {
        Scanner cin = new Scanner(System.in);
        while (cin.hasNext())
        {
            String st = cin.next();
            int a = cin.nextInt();
            int b = cin.nextInt();
            BigInteger bigA = new BigInteger(st, a);
            StringBuffer ans = new StringBuffer(bigA.toString(b));
            if (ans.length() > 7)
            {
                System.out.println("  ERROR");
                continue;
            }
            for (int i = 0; i < ans.length(); i++)
                if (ans.charAt(i) <= 'z' && ans.charAt(i) >= 'a')
                    ans.setCharAt(i, (char)('A' - 'a' + ans.charAt(i)));
            int len = ans.length();
            for (int i = len; i < 7; i++)
                ans.insert(0,  ' ');
            System.out.println(ans.toString());
        }
    }
}