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Description:
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,
Solution:
long division: 长除法
Trick： Determining whether two nums have different sign(+ or -) can use follow codes:
if((n<0)^(d<0)) //异号 or if((n>0)^(d>0)) //异号
Above code avoiding product‘s value overflow.
Code:
class Solution { public: string fractionToDecimal(int numerator, int denominator) { if(!numerator) return "0"; long long n = numerator, d = denominator; string ret = ""; if((n<0)^(d<0)) ret += ‘-‘; if(n < 0) n = -n; if(d < 0) d = -d; ret += to_string(n/d); if(n % d == 0){ return ret; }ret += ‘.‘; map<long long, int>hash; for(long long r = n % d; r; r %= d){ if(hash.find(r) != hash.end()){ ret.insert(hash[r],"("); ret += ")"; return ret; } hash[r] = ret.size(); r *= 10; ret += to_string(r / d); } } };
【Leetcode 166】 Fraction to Recurring Decimal
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原文地址：http://www.cnblogs.com/luntai/p/5862823.html
