public:

string fractionToDecimal(int numerator, int denominator) {

if (numerator == 0) return "0";

if (denominator == 0) return "";

string ans = "";

//如果结果为负数

if ((numerator < 0) ^ (denominator < 0)) {

ans += "-";

}

//下面要把两个数都转为正数，为避免溢出，int转为long

long num = numerator, den = denominator;

num = Math.abs(num);

den = Math.abs(den);

//结果的整数部分

long res = num / den;

ans += string.valueOf(res);

//如果能够整除，返回结果

long rem = (num % den) * 10;

if (rem == 0) return ans;

//结果的小数部分

HashMap<Long, Integer> map = new HashMap<Long, Integer>();

ans += ".";

while (rem != 0) {

//如果前面已经出现过该余数，那么将会开始循环

if (map.containsKey(rem)) {

int beg = map.get(rem); //循环体开始的位置

string part1 = ans.substring(0, beg);

string part2 = ans.substring(beg, ans.length());

ans = part1 + "(" + part2 + ")";

return ans;

}

//继续往下除

map.put(rem, ans.length());

res = rem / den;

ans += string.valueOf(res);

rem = (rem % den) * 10;

}

return ans;

}

{

/* code */

return 0;

}