leetcode 166 分数到小数

我是傻逼。若结果中出现循环，每一次获得的余数也会是循环，所以用一个哈希表来存放所有的余数，当余数出现重复时，代表结果中也出现了重复，从而将左括号插入该余数的下标处，从而完成任务，贴代码

class Solution {
public:
    string fractionToDecimal(int numerator, int denominator) 
    {
        string res;
        long n = 0;
        long d = 0;
        long flag = 1;
        if(numerator == INT_MIN && denominator == -1)
        {
            n = long(INT_MAX)+1;
            d = 1;
            flag = 1;
        }
        else
        {
            n = numerator>=0 ? numerator:-1*long(numerator);
            d = denominator>0 ? denominator:-1*long(denominator);
            flag = (numerator>=0 && denominator>0) || (numerator<0 && denominator<0) ? 1:-1;
        }
        if(n == 0)
        return "0";
        if(flag == -1)
        res+='-';
        res.append(to_string(n/d));           
        n = n%d;
        if(n == 0)
        return res;
        res+='.';
        int index = res.size()-1;
        unordered_map<int,int> record;
        while(n && record.count(n) == 0)
        {
            record[n] = ++index;
            n *= 10;
            res += to_string(n/d);
            n = n%d;
        }
        if(record.count(n) == 1)
        {
            res.insert(record[n],"(");
            res.push_back(')');
        }
        return res;
    }
};