Created
January 22, 2013 01:52
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import java.math.BigInteger; | |
import java.io.File; | |
import java.io.FileOutputStream; | |
public class BaseConvert | |
{ | |
public static void main(String[] args) throws Throwable | |
{ | |
if(args.length < 3) | |
{ | |
java.util.Scanner in = new java.util.Scanner(System.in); | |
System.out.println(ConvertBase(in.next(), (char)in.nextInt(), (char)in.nextInt())); | |
} | |
else if(args.length == 3) | |
{ | |
System.out.println(ConvertBase(args[0], Integer.parseInt(args[1]), Integer.parseInt(args[2]))); | |
} | |
else if(args.length == 4) | |
{ | |
String s = ConvertBase(args[0], Integer.parseInt(args[1]), Integer.parseInt(args[2])); | |
File f = new File(args[4]); | |
if(!f.exists()) | |
{ | |
f.createNewFile(); | |
} | |
FileOutputStream ofs = new FileOutputStream(f); | |
ofs.write(s.getBytes()); | |
ofs.flush(); | |
ofs.close(); | |
} | |
} | |
static String ConvertBase(String num, final int from, final int to) | |
{ | |
if(from < 2 || from > 62 || to < 2 || to > 62) return null; | |
final BigInteger bi_from = new BigInteger(""+from); | |
final BigInteger bi_to = new BigInteger(""+to); | |
BigInteger n = BigInteger.ZERO; | |
String sign = ""; | |
if(num.charAt(0) == '-') | |
{ | |
sign = "-"; | |
num = num.substring(1); | |
} | |
int dig = 0; | |
for(char c : new StringBuilder(num).reverse().toString().toCharArray()) | |
{ | |
int d; | |
if(c >= '0' && c <= '9') | |
{ | |
d = c-'0'; | |
} | |
else if(c >= 'A' && c <= 'Z') | |
{ | |
d = c-'A'+10; | |
} | |
else if(c >= 'a' && c <= 'z') | |
{ | |
d = c-'a'+36; | |
} | |
else return null; | |
n = n.add(bi_from.pow(dig++).multiply(new BigInteger(""+d))); | |
} | |
StringBuilder sb = new StringBuilder(); | |
while(!n.equals(BigInteger.ZERO)) | |
{ | |
int d = n.mod(bi_to).intValue(); | |
if(d >= 0 && d <= 9) | |
{ | |
d = '0'+d; | |
} | |
else if(d >= 10 && d <= 35) | |
{ | |
d = 'A'+d-10; | |
} | |
else | |
{ | |
d = 'a'+d-36; | |
} | |
sb.append((char)d); | |
n = n.divide(bi_to); | |
} | |
return sign+sb.reverse(); | |
} | |
} |
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