166 Fraction to Recurring Decimal

166 Fraction to Recurring Decimal

这道题就是不停的去check做除法的余数是否重复出现了

 

class Solution:
    # @param {integer} numerator
    # @param {integer} denominator
    # @return {string}
    def fractionToDecimal(self, n, d):
        isNeg = (n * d < 0)
        n, d = abs(n), abs(d)
        ans= ''
        ans += str(n/d)
        if isNeg:
            ans = '-' + ans
        if n % d == 0:
            return ans
        ans += '.'
        dic = {}
        n = n % d
        while True:
            if n not in dic:
                dic[n] = len(ans)
            else:
                pos = dic[n]
                return ans[:pos] + "(" + ans[pos:] + ")"
            n *= 10
            if n % d == 0:
                ans += str(n/d)
                return ans
            else:
                r = n / d
                n %= d
                ans += str(r)