Merge pull request #153 from TimoSci/bfs

Bfs

06_breadth-first_search/ruby/01_breadth-first_search.rb

@@ -1,40 +1,39 @@
-def person_is_seller(name)
+def person_is_seller?(name)
   name[-1] == "m"
 end
 
-@graph = {}
+class Graph < Hash
+  def search(name)
+    search_queue = []
+    search_queue += self[name]
+    # The "searched" Hash is how you keep track of which people you've searched before. We use a hash because hash lookups are fast!
+    searched = {}
 
-# %w(string1 string2 ...) is a shorter way to define arrays of strings
-@graph["you"] = %w(alice bob claire)
-@graph["bob"] = %w(anuj peggy)
-@graph["alice"] = %w(peggy)
-@graph["claire"] = %w(thom jonny)
-@graph["anuj"] = []
-@graph["peggy"] = []
-@graph["thom"] = []
-@graph["jonny"] = []
-
-def search(name)
-  search_queue = []
-  search_queue += @graph[name]
-  # This array is how you keep track of which people you've searched before.
-  searched = []
-
-  until search_queue.empty?
-    person = search_queue.shift
-    # Only search this person if you haven't already searched them.
-    next if searched.member?(person)
-    if person_is_seller(person)
-      puts "#{person} is a mango seller!"
-      return true
-    else
-      search_queue += @graph[person]
+    until search_queue.empty?
+      person = search_queue.shift
+      # Only search this person if you haven't already searched them.
+      next if searched[person]
+      return person if yield person
+      search_queue += self[person]
       # Marks this person as searched
-      searched.push(person)
+      searched[person] = true
     end
-  end
 
-  false
+    false
+  end
 end
 
-search("you")
+
+# %w(string1 string2 ...) is a shorter way to define arrays of strings
+graph = Graph.new
+graph["you"] = %w(alice bob claire)
+graph["bob"] = %w(anuj peggy)
+graph["alice"] = %w(peggy)
+graph["claire"] = %w(thom jonny)
+graph["anuj"] = []
+graph["peggy"] = []
+graph["thom"] = []
+graph["jonny"] = []
+
+# we begin the search from vertex "you" and pass the match criterion in the block, then we tap the search result
+graph.search("you"){|person| person_is_seller?(person)}.tap{|person| puts "#{person} is a mango seller!" if person}