FractionToRecurringDecimal

Change-Id: I47107ffba8924a2540c4fb5a4371ddbe5b8b1c06

Author: applewjg

FractionToRecurringDecimal.h

@@ -0,0 +1,48 @@
+/*
+ Author:     King, [email protected]
+ Date:       Dec 15, 2014
+ Problem:    Fraction to Recurring Decimal
+ Difficulty: Easy
+ Source:     https://oj.leetcode.com/problems/fraction-to-recurring-decimal/
+ Notes:
+ 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)".
+
+ Solution: ...
+ */
+class Solution {
+public:
+    string fractionToDecimal(int numerator, int denominator) {
+        if (numerator == 0) return string("0");
+        bool flag = (numerator < 0)^(denominator < 0);
+        long long Numerator = abs((long long)numerator);
+        long long Denominator = abs((long long)denominator);
+        string res;
+        if (flag == true) res.push_back('-');
+        ostringstream out;
+        out << (Numerator / Denominator);
+        res.insert(res.size(),out.str());
+        Numerator = Numerator % Denominator;
+        if (Numerator == 0) return res;
+        res.push_back('.');
+        unordered_map<int, int> map;
+        for (int i = res.size(); Numerator != 0; ++i) {
+            if (map.find(Numerator) != map.end()) break;
+            map[Numerator] = i;
+            Numerator *= 10;
+            res.push_back((Numerator / Denominator) + '0');
+            Numerator %= Denominator;
+        }
+        if (Numerator == 0) return res;
+        res.insert(map[Numerator],"(");
+        res.push_back(')');
+        return res;
+    }
+};