[leetcode]166. 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)".

分数转变为小数，无限循环部分括起来

class Solution(object):
    def fractionToDecimal(self, numerator, denominator):
        n,remainder = divmod(abs(numerator),abs(denominator))
        flag = '-' if numerator*denominator<0 else ''
        res = [flag+str(n),'.']
        s = []
        while remainder not in s:
            s.append(remainder)
            n,remainder = divmod(remainder*10,abs(denominator))
            res.append(str(n))
        i = s.index(remainder)
        res.insert(i+2,'(')
        res.append(')')
        return ''.join(res).replace('(0)','').rstrip('.')