Refactor: new line at the end of the code

Author: obzva

contains-duplicate/flynn.cpp

@@ -21,4 +21,4 @@ class Solution {
         }
         return false;
     }
-};
+};

kth-smallest-element-in-a-bst/flynn.cpp

@@ -38,4 +38,4 @@ class Solution {
 
         return nums[k - 1];
     }
-};
+};

number-of-1-bits/flynn.cpp

@@ -18,4 +18,4 @@ class Solution {
 
         return res;
     }
-};
+};

palindromic-substrings/flynn.cpp

@@ -31,4 +31,4 @@ class Solution {
 
         return res;
     }
-};
+};

top-k-frequent-elements/flynn.cpp

@@ -43,4 +43,4 @@ class Solution {
 
         return res;
     }
-};
+};