Binary Representation

Given a (decimal - e.g. 3.72) number that is passed in as a string, return the binary representation that is passed in as a string. If the fractional part of the number can not be represented accurately in binary with at most 32 characters, return ERROR.

Example

For n = "3.72", return "ERROR".

For n = "3.5", return "11.1".

分析：

分成两个部分，整数部分用%和/，小数部分 *2 如果 <1 就为0，基数=基数；大于1,就为1,基数=基数-1

比如：
0.6*2=1.2>0 那么就为1 基数=1.2-1=0.2

0.2*2=0.4<0 那么就为0,基数=0.4

0.4*2=0.8<0,那么就为0,基数=0.8

0.8*2=1.6>0 那么就为1,基数为1.6-1=0.6
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:
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所以5.6可以表示为:101.1001

 public class Solution {
     /**
      *@param n: Given a decimal number that is passed in as a string
      *@return: A string
      */
     public String binaryRepresentation(String n) {
         int intPart = Integer.parseInt(n.substring(, n.indexOf('.')));
         double decPart = Double.parseDouble(n.substring(n.indexOf('.')));
         String intstr = "";
         String decstr = "";

         if (intPart == ) intstr += '';
         while (intPart > ) {
             int c = intPart % ;
             intstr = c + intstr;
             intPart = intPart / ;
         }
        int count = ;
         while (decPart > 0.0 && count <= ) {
             double r = decPart * ;
             if (r >= 1.0) {
                 decstr += '';
                 decPart = r - 1.0;
             }else {
                 decstr += '';
                 decPart = r;
             }
             count++;
         }

         if (count > ) return "ERROR";
         return decstr.length() > ? intstr + "." + decstr : intstr;
     }
 }