Update dynamic_programming/word_break.cpp

Co-authored-by: David Leal <halfpacho@gmail.com>

dynamic_programming/word_break.cpp

@@ -36,6 +36,16 @@ using std::string;
 using std::unordered_set;
 using std::vector;
 
+/**
+ * @namespace dynamic_programming
+ * @brief Dynamic programming algorithms
+ */
+namespace dynamic_programming {
+/**
+ * @namespace word_break
+ * @brief Functions for Word Break algorithm
+ */
+namespace word_break {
 /**
  * @brief Solution class
  */