Fraction to Recurring Decimal

long n = (long) numerator>0? numerator: -numerator;
long d = (long) denominator>0? denominator:-denominator;

public class Solution {
    public String fractionToDecimal(int numerator, int denominator) {
        // 我觉得特别清晰受益的一个解法https://leetcode.com/discuss/27159/my-java-solution
       // long n = Math.abs(numerator), d = Math.abs(denominator);// 可能是特别大的数不能这么写
       long n = numerator;
       long d = denominator;
       n = n>0? n:-n;
       d = d>0? d:-d;
        // 不要忘了全部变正数
        
        String s = Long.toString(n/d);
        int index = 0; 
        HashMap<Long, Integer> hm = new HashMap<Long, Integer>();
        n = n%d;
        if(n!=0)
            s += ".";
        index += s.length(); // current digit‘s position，//idx放在这里才会及时反映出，小数点后的位置
        
        //不断乘以10求得小数点后的位数
        while(n>0){
            if(hm.get(n)==null)
                hm.put(n, index);
            else{
                s = s.substring(0,hm.get(n)) + "(" + s.substring(hm.get(n),index) + ")";
                break;
            }
            n *=10;
            s += Long.toString(n/d);
            n %= d;
            index++;
        }
        
        // if(numerator*denominator<0) s = "-"+s;// 可能是特别大的数不能这么写
        if((numerator<0&&denominator>0) ||(numerator>0&& denominator<0)) s = "-"+s;
        return s;
    }
}