Fraction to Recurring Decimal.java

class Solution {
    public String fractionToDecimal(int numerator, int denominator) {
        if(numerator == 0){
            return  "0";
        }
        
        StringBuilder sb = new StringBuilder("");
        if(numerator<0 && denominator>0 || numerator>0 && denominator<0){
            sb.append("-");
        }
        
        long divisor = Math.abs((long)numerator);
        long dividend = Math.abs((long)denominator);
        long remainder = divisor % dividend;
        sb.append(divisor / dividend);
        
        if(remainder == 0){
            return sb.toString();
        }
        sb.append(".");
        HashMap<Long, Integer> map = new HashMap<Long, Integer>();
        while(remainder!=0){
            if(map.containsKey(remainder)){
                sb.insert(map.get(remainder), "(");
                sb.append(")");
                break;
            }
            map.put(remainder, sb.length());
            remainder*= 10;
            sb.append(remainder/dividend);
            remainder%= dividend;
        }
        return sb.toString();
    }
}