Update linked-list-cycle.cpp

Author: kamyu104

C++/linked-list-cycle.cpp

@@ -16,10 +16,10 @@ class Solution {
 
         while (fast && fast->next) {
             slow = slow->next, fast = fast->next->next;
-            if (slow == fast) {
+            if (slow == fast) {  // There is a cycle.
                 return true;
             }
         }
-        return false;
+        return false;  // No cycle.
     }
 };