Create 166. Fraction to Recurring Decimal

166. Fraction to Recurring Decimal

@@ -0,0 +1,34 @@
+class Solution {
+public:
+    string fractionToDecimal(int numerator, int denominator) {
+
+        if (numerator == 0) return "0";
+        string res;
+        if ((numerator < 0) ^ (denominator < 0)) res.push_back('-');
+
+        long long n = llabs((long long)numerator);
+        long long d = llabs((long long)denominator);
+
+        res += to_string(n / d);
+        long long rem = n % d;
+        if (rem == 0) return res;
+
+        res.push_back('.');
+        unordered_map<long long, int> seen;
+
+        while (rem != 0) {
+            if (seen.find(rem) != seen.end()) {
+                int pos = seen[rem];
+                res.insert(pos, "(");
+                res.push_back(')');
+                break;
+            }
+            seen[rem] = res.size();
+            rem *= 10;
+            int digit = rem / d;
+            res.push_back(char('0' + digit));
+            rem = rem % d;
+        }
+        return res;
+    }
+};