leetcode 166

我的想法很简单, 先存一下符号, 然后从小数第一位开始进行记录, 每次都乘10 相除, 直到遇到重复的, 为了防止溢出用了long long

class Solution {
public:
    string fractionToDecimal(int numerator, int denominator) {
        if (0 == numerator){
            return "0";
        }
        long long num = numerator, den = denominator, tmp;
        // map<long long, int> num_map;
        set<long long> num_set;
        vector<long long> result_int, tmp_list;
        string result = "";
        bool postive = false;
        // int i = 0;
        if ((num < 0 and den < 0) or (num > 0 and den > 0)){
            postive = true;
        }else {
            postive = false;
        }
        if (false == postive){
            result.append("-");
        }
        if (num < 0){
            num = -1 * num;
        }
        if (den < 0){
            den = -1 * den;
        }

        // result_int.push_back(num / den);
        result.append(to_string(num / den));

        tmp = num % den;
        if (0 == tmp){
            return result;
        }
        result.append(".");

        while (0 != tmp){
            tmp *= 10;
            if (num_set.find(tmp) != num_set.end()){
                break;
            }
            num_set.insert(tmp);
            result_int.push_back(tmp / den);
            tmp_list.push_back(tmp);
            tmp = tmp % den;
        }

        if (0 == tmp){
            for (vector<long long>::iterator i = result_int.begin(); i != result_int.end(); i++){
                result.append(to_string(*i));
            }
        }else{
            for(int i = 0; i < result_int.size(); i++){
                
                if (tmp == tmp_list[i]){
                    result.append("(");
                }
                result.append(to_string(result_int[i]));
            }
            result.append(")");
        }
        return result;

    }
};