12.Integer to Roman

    /*
     * 12.Integer to Roman  
     * 2016-4-14 by Mingyang
     * 这里我先忘掉了50和40，然后在499还是490之间纠结了一会
     * 另外if判断句里面 if(num>=array[i])是大于等于不是只有大于，不然9过不去
     */
     public static String intToRoman(int num) {
            String res="";
            if(num<=0)
              return res;
          int[] array={1,4,5,9,10,40,50,90,100,400,500,900,1000};
          String[] str={"I","IV","V","IX","X","XL","L","XC","C","CD","D","CM","M"};
          StringBuffer sb=new StringBuffer();
          while(num>0){
              for(int i=array.length-1;i>=0;i--){
                  if(num>=array[i]){
                      int tem=num/array[i];
                      while(tem>0){
                       sb.append(str[i]);
                       tem--;
                      }
                      num=num%array[i];
                  }
              }
          }
          return sb.toString();
        }