166. Fraction to Recurring Decimal

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)".

Hint:
No scary math, just apply elementary math knowledge. Still remember how to perform a long division?
Try a long division on 4/9, the repeating part is obvious. Now try 4/333. Do you see a pattern?
Be wary of edge cases! List out as many test cases as you can think of and test your code thoroughly.

Code:

public class Solution {
public String fractionToDecimal(int numerator, int denominator) {
return getInt(numerator,denominator) + getDec(numerator,denominator);

}

String getInt(int num, int denum){
String sign = ((num > 0) == (denum > 0) || num == 0) ? "" : "-";
long n = Math.abs((long) num);
long dn = Math.abs((long) denum);
return sign + (n/dn);
}

String getDec(int num, int denum){
long n = Math.abs((long) num);
long dn = Math.abs((long) denum);
n = n % dn;
if(n == 0) return "";
HashMap<Long,Integer> hm = new HashMap<>();
StringBuilder sb = new StringBuilder();
sb.append(".");
while(n != 0 && !hm.containsKey(n)){
long t = (n * 10) / dn;
hm.put(n,sb.length());
sb.append(t);
n = (n * 10) % dn;

}
if(n != 0){
sb.insert(hm.get(n),"(");
sb.append(")");
}
return sb.toString();
}
}