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:

1. No scary math, just apply elementary math knowledge. Still remember how to perform a long division?
2. Try a long division on 4/9, the repeating part is obvious. Now try 4/333. Do you see a pattern?
3. 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();    }}