Create custom-sort-string.cpp

Author: kamyu104

C++/custom-sort-string.cpp

@@ -0,0 +1,23 @@
+// Time:  O(n)
+// Space: O(1)
+
+class Solution {
+public:
+    string customSortString(string S, string T) {
+        unordered_set<char> s(S.cbegin(), S.cend());
+        unordered_map<char, int> counter;
+        for (const auto& c : T) {
+            ++counter[c];
+        }
+        string result;
+        for (const auto& c : S) {
+            result += string(counter[c], c);
+        }
+        for (const auto& kvp : counter) {
+            if (!s.count(kvp.first)) {
+                result += string(kvp.second, kvp.first);
+            }
+        } 
+        return result;
+    }
+};