Create reformat-date.cpp

Author: kamyu104

C++/reformat-date.cpp

@@ -0,0 +1,22 @@
+// Time:  O(n)
+// Space: O(1)
+
+class Solution {
+public:
+    string reformatDate(string date) {
+        static const unordered_map<string, int> lookup = {
+            {"Jan", 1}, {"Feb", 2}, {"Mar", 3}, {"Apr", 4},
+            {"May", 5}, {"Jun", 6}, {"Jul", 7}, {"Aug", 8},
+            {"Sep", 9}, {"Oct", 10}, {"Nov", 11}, {"Dec", 12}
+        };
+        stringstream ss;
+        int y = stoi(date.substr(date.length() - 4));
+        ss << setfill('0') << setw(4) << y;
+        int m = lookup.at(date.substr(date.length() - 4 - 4, 3));
+        ss << "-" << setfill('0') << setw(2) << m;
+        int d = stoi(date.substr(0, date.find(' ', 0) - 2));
+        ss << "-" << setfill('0') << setw(2) << d;
+        return ss.str();
+    }
+};
+