P.1: Fixed incorrect use of `std::find`.

CppCoreGuidelines.md

@@ -387,7 +387,7 @@ A much clearer expression of intent would be:
         string val;
         cin >> val;
         // ...
-        auto p = find(v, val);  // better
+        auto p = find(begin(v), end(v), val);  // better
         // ...
     }