visitor.h:1:  Line ends in whitespace.  Consider deleting these extra spaces.  [whitespace/end_of_line] [4]
visitor.h:3:  public: should be indented +1 space inside class BfsVisitor  [whitespace/indent] [3]
visitor.h:22:  An else should appear on the same line as the preceding }  [whitespace/newline] [4]
visitor.h:22:  If an else has a brace on one side, it should have it on both  [readability/braces] [5]
visitor.h:31:  private: should be indented +1 space inside class BfsVisitor  [whitespace/indent] [3]
visitor.h:31:  "private:" should be preceded by a blank line  [whitespace/blank_line] [3]
visitor.h:32:  Add #include <map> for map<>  [build/include_what_you_use] [4]
Done processing visitor.h
Total errors found: 7