- 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)"
解 当余数重复出现时，意味着循环节出现了。因此需要用一个字典pos记录每个余数出现的位置，重复出现的余数对应的两个位置之间的即为循环节
Note: 运行时发现数字会出现溢出的问题，代码中的类型改成了long long int
class Solution {
public:
string fractionToDecimal(long long int numerator, int denominator) {
string res;
if(numerator < 0 && denominator > 0){
numerator *= -1;
res += "-";
}else if(numerator > 0 && denominator < 0){
denominator *= -1;
res += "-";
}
res += to_string(divmod(numerator, denominator));
if(numerator == 0)return res;
res += ".";
map<int, int>mp;
mp[numerator] = res.size();
while(numerator){
numerator *= 10;
int tmp = divmod(numerator, denominator);
res += to_string(tmp);
if(mp.find(numerator) != mp.end()){
res.insert(mp[numerator], "(");
res += ")";
break;
}
mp[numerator] = res.size();
}
return res;
}
long long int divmod(long long int &n1, int &n2){
long long int res = n1 / n2;
n1 -= res * n2;
return res;
}
};