Add recursive debug

Author: soycode

graph_dfs_debug/README.md

@@ -19,6 +19,11 @@ this part didn't really work.
 5. My editor sure is complaining a lot about something called "lint."
 6. I keep losing track of my variables, I guess I should name them better?
 
+I also tried to do it with recursion instead of a stack, in `graph_rec`, but I
+got even more stuck. It was running forever so I tried adding a thing to keep
+track of vertices, and now I just get an error message. Please try to fix this
+too if you can, or at least give me some pointers on what I should be doing.
+
 I'm still trying to learn this stuff, so please don't just fix the code for me.
 Let me know in the `Answers.md` file where my bugs are and what you did to fix
 them, so I can have an easier time watching out for them next time. Oh and don't

graph_dfs_debug/graph.py

@@ -36,6 +36,13 @@ def dfs(self, start, target=None):
 
         return x
 
+    def graph_rec(self, start, target=None):
+        x = set()
+        x.append(start)
+        for v in self.vertices[start]:
+            graph_rec(v)
+        return x
+
     def find_components(self):
         visited = set()
         current_component = 0