Given two integers representing the numerator and denominator of a fraction, return the fraction in string format.

If the fractional part is repeating, enclose the repeating part in parentheses.

For example,

Given numerator = 1, denominator = 2, return "0.5".
Given numerator = 2, denominator = 1, return "2".
Given numerator = 2, denominator = 3, return "0.(6)".
Credits:
Special thanks to @Shangrila for adding this problem and creating all test cases.

public String fractionToDecimal(int numerator, int denominator) {
            long num = (long)numerator;
            long den = (long)denominator;
            boolean isNeg = false;
            if (num < 0) isNeg = !isNeg;
            if (den < 0) isNeg = !isNeg;
            num = Math.abs(num);
            den = Math.abs(den);
            HashMap<Long, Integer> dict = new HashMap<Long, Integer>();
            StringBuffer res = new StringBuffer();
            if (num == 0) return "0";
            long digit = num / den; //deal with integer part
            res.append(digit);
            num = (num % den) * 10;
            if (num != 0) res.append("."); //deal with decimal point
            else return res.toString();
            while (num != 0 && !dict.containsKey(num)) {
                dict.put(num, res.length());
                digit = num / den;
                res.append(digit);
                num = (num % den) * 10;
            }
            if (dict.containsKey(num)) {
                res.insert(dict.get(num).intValue(), ‘(‘);
                res.append(‘)‘);
            }
            if (isNeg) res.insert(0, ‘-‘);
            return res.toString();
        }