[leetCode] 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)".

class Solution {public:    string fractionToDecimal(int numerator, int denominator) {        string ans = "";        long long nume = numerator;        long long deno = denominator;        if(denominator == 0)return ans;        if(numerator == 0) return "0";        if(denominator < 0 ^ numerator < 0) {            ans += '-';            nume = abs(nume);            deno = abs(deno);        }        ans += to_string(nume / deno);        long long rem = nume % deno * 10;        if(rem == 0) return ans;        ans += '.';        map<long long,int> m;        long long res = 0;        while(rem){            if(m.find(rem) != m.end()){                int begin = m[rem];                string s1 = ans.substr(0,begin);                string s2 = ans.substr(begin);                ans = s1 + '(' + s2 + ')';                break;            }            m[rem] = ans.length();            res = rem / deno;            ans += to_string(res);            rem = rem % deno * 10;        }        return ans;    }};