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.

Example 1:

Input: numerator = 1, denominator = 2
Output: "0.5"

Example 2:

Input: numerator = 2, denominator = 1
Output: "2"

Example 3:

Input: numerator = 2, denominator = 3
Output: "0.(6)"

 

Approach #1: C++

class Solution {
public:
    typedef long long LL;
    string fractionToDecimal(int numerator, int denominator) {
        if (!numerator) return "0";
        string res;
        if (numerator < 0 ^ denominator < 0) res += '-';
        LL numer = numerator < 0 ? (LL)numerator * (-1) : (LL)numerator;
        LL denom = denominator < 0 ? (LL)denominator * (-1) : (LL)denominator;
        LL quotient = numer / denom;
        LL remainder = numer % denom;
        res += to_string(quotient);
        if (!remainder) return res;
        res += '.';
        remainder *= 10;
        cout << remainder << endl;
        unordered_map<LL, LL> mp;
        while (remainder) {
            quotient = remainder / denom;
            if (mp.find(remainder) != mp.end()) {
                res.insert(mp[remainder], 1, '(');
                res += ')';
                break;
            }
            mp[remainder] = res.size();
            res += to_string(quotient);
            remainder = (remainder % denom) * 10;
        }
        return res;
    }
};

　　

Approach #2: Java

class Solution {
    public String fractionToDecimal(int numerator, int denominator) {
        StringBuilder result = new StringBuilder();
        String sign = (numerator < 0 == denominator < 0 || numerator == 0) ? "" : "-";
        long num = Math.abs((long) numerator);
        long den = Math.abs((long) denominator);
        result.append(sign);
        result.append(num / den);
        long remainder = num % den;
        if (remainder == 0)
            return result.toString();
        result.append(".");
        HashMap<Long, Integer> hashMap = new HashMap<Long, Integer>();
        while (!hashMap.containsKey(remainder)) {
            hashMap.put(remainder, result.length());
            result.append(10 * remainder / den);
            remainder = 10 * remainder % den;
        }
        int index = hashMap.get(remainder);
        result.insert(index, "(");
        result.append(")");
        return result.toString().replace("(0)", "");
    }
};

　　

Approach #3: Python

class Solution(object):
    def fractionToDecimal(self, numerator, denominator):
        """
        :type numerator: int
        :type denominator: int
        :rtype: str
        """
        res = ""
        if numerator/denominator < 0:
            res += '-'
        if numerator%denominator == 0:
            return str(numerator/denominator)
        numerator = abs(numerator)
        denominator = abs(denominator)
        res += str(numerator/denominator)
        res += '.'
        numerator %= denominator
        i = len(res)
        table = {}
        while numerator != 0:
            if numerator not in table.keys():
                table[numerator] = i
            else:
                i = table[numerator]
                res = res[:i] + "(" + res[i:] + ")"
                return res
            numerator = numerator * 10
            res += str(numerator/denominator)
            numerator %= denominator
            i += 1
        return res
        
        

In this case if we use Python3 it will report error.

Time Submitted	Status	Runtime	Language
a few seconds ago	Accepted	32 ms	python
11 minutes ago	Accepted	6 ms	java
23 minutes ago	Accepted	0 ms	cpp