Release/v0.16.0

lib/algorithmable.rb

@@ -14,6 +14,7 @@ module Algorithmable
   autoload :LevenshteinDistance, 'algorithmable/levenshtein_distance'
   autoload :Cups, 'algorithmable/cups'
   autoload :Cache, 'algorithmable/cache'
+  autoload :Trees, 'algorithmable/trees'
   autoload :UnionFind, 'algorithmable/union_find'
 
   class << self

lib/algorithmable/data_structs/linked_list/doubly.rb

@@ -2,18 +2,6 @@ module Algorithmable
   module DataStructs
     module LinkedList
       class Doubly < Base
-        class Node
-          attr_accessor :item, :prev, :next, :front
-
-          def initialize(item, prev_pointer = nil, next_pointer = nil)
-            @item = item
-            @prev = prev_pointer
-            @next = next_pointer
-          end
-        end
-
-        private_constant :Node
-
         def push_front(item)
           prev_front = @front
           node = new_node item, nil, prev_front
@@ -80,6 +68,18 @@ def delete(item)
         def new_node(item, prev_pointer = nil, next_pinter = nil)
           Node.new item, prev_pointer, next_pinter
         end
+
+        class Node
+          attr_accessor :item, :prev, :next, :front
+
+          def initialize(item, prev_pointer = nil, next_pointer = nil)
+            @item = item
+            @prev = prev_pointer
+            @next = next_pointer
+          end
+        end
+
+        private_constant :Node
       end
     end
   end

lib/algorithmable/data_structs/linked_list/singly.rb

@@ -2,16 +2,6 @@ module Algorithmable
   module DataStructs
     module LinkedList
       class Singly < Base
-        class Node
-          attr_accessor :item, :next, :front
-
-          def initialize(item, next_pointer = nil)
-            @item = item
-            @next = next_pointer
-          end
-        end
-
-        private_constant :Node
 
         def push_front(obj)
           node = new_node(obj)
@@ -182,6 +172,17 @@ def remove_next(prev)
         def new_node(item, next_pinter = nil)
           Node.new item, next_pinter
         end
+
+        class Node
+          attr_accessor :item, :next, :front
+
+          def initialize(item, next_pointer = nil)
+            @item = item
+            @next = next_pointer
+          end
+        end
+
+        private_constant :Node
       end
     end
   end

lib/algorithmable/data_structs/ordered_symbol_table.rb

@@ -2,12 +2,14 @@ module Algorithmable
   module DataStructs
     class OrderedSymbolTable
       extend Forwardable
+      include Algorithmable::Trees
+
+      private_methods :new_binary_search_tree
 
       def_delegators :@imp, :[]=, :[], :key?, :empty?, :size, :keys, :max, :min, :floor, :ceiling, :rank, :delete
 
       def initialize(key_type, value_type)
-        search_strategy_factory = Object.new.extend Algorithmable::Searches
-        @imp = search_strategy_factory.new_binary_search_tree(key_type, value_type)
+        @imp = new_binary_search_tree(key_type, value_type)
       end
     end
   end

lib/algorithmable/graphs.rb

@@ -1,7 +1,9 @@
 module Algorithmable
   module Graphs
-    autoload :Undirected, 'algorithmable/graphs/undirected'
-    autoload :Traversals, 'algorithmable/graphs/traversals'
+    require 'algorithmable/graphs/directed'
+    require 'algorithmable/graphs/edge'
+    require 'algorithmable/graphs/traversals'
+    require 'algorithmable/graphs/undirected'
 
     class << self
       def new_undirected_graph(vertices = [])
@@ -11,6 +13,14 @@ def new_undirected_graph(vertices = [])
         end
         graph
       end
+
+      def new_directed_graph(vertices = [])
+        Directed.new.tap do |g|
+          vertices.each do |from, to, weight|
+            g.add_edge Edge.new(from, to, weight)
+          end
+        end
+      end
     end
   end
 end

lib/algorithmable/graphs/directed.rb

@@ -0,0 +1,45 @@
+module Algorithmable
+  module Graphs
+    class Directed
+      def initialize
+        @edges = 0
+        @incoming_degree = []
+        @adjacency_list = []
+      end
+
+      def add_edge(edge)
+        from = edge.from
+        to = edge.to
+        validate_vertex(to)
+        validate_vertex(from)
+        (@adjacency_list[from] ||= [])
+            .tap { |xs| xs << edge }
+        (@incoming_degree[to] ||= 0)
+            .tap { @incoming_degree[to] += 1 }
+        @edges += 1
+      end
+
+      def adjacency_list(vertex)
+        @adjacency_list[vertex] || []
+      end
+
+      def out_degree(vertex)
+        @adjacency_list[vertex].length
+      end
+
+      def in_degree(vertex)
+        @incoming_degree[vertex]
+      end
+
+      def edges
+        @adjacency_list.dup
+      end
+
+      private
+
+      def validate_vertex(value)
+        raise "invalid vertex value: #{value}" if 0 > value
+      end
+    end
+  end
+end

lib/algorithmable/graphs/edge.rb

@@ -0,0 +1,14 @@
+module Algorithmable
+  module Graphs
+    class Edge
+      attr_reader :from, :to, :weight
+
+      def initialize(from, to, weight)
+        @from = from
+        @to = to
+        @weight = weight
+        freeze
+      end
+    end
+  end
+end

lib/algorithmable/graphs/traversals.rb

@@ -1,9 +1,10 @@
 module Algorithmable
   module Graphs
     module Traversals
-      autoload :Errors, 'algorithmable/graphs/traversals/errors'
-      autoload :DepthFirst, 'algorithmable/graphs/traversals/depth_first'
-      autoload :BreadthFirst, 'algorithmable/graphs/traversals/breadth_first'
+      require 'algorithmable/graphs/traversals/errors'
+      require 'algorithmable/graphs/traversals/depth_first'
+      require 'algorithmable/graphs/traversals/breadth_first'
+      require 'algorithmable/graphs/traversals/topological_sort'
 
       def traverse_with_depth_first(graph, source)
         DepthFirst.new(graph, source)

lib/algorithmable/graphs/traversals/breadth_first.rb

@@ -5,12 +5,12 @@ module Traversals
       class BreadthFirst
         include Algorithmable::Graphs::Traversals::Errors
 
-        def initialize(graph, source)
+        def initialize(graph, source, &f)
           vertices_size = graph.vertices.size
           @visited = Array.new(vertices_size - 1)
           @edge_to = Array.new(vertices_size - 1)
           @source = source
-          traverse graph, source
+          traverse graph, source, &f
         end
 
         def visited?(vertex)
@@ -22,10 +22,10 @@ def path_to(vertex)
           path = []
           finish = vertex
           while finish != @source
-            path.push finish
+            path.unshift finish
             finish = @edge_to[finish]
           end
-          path.push @source
+          path.unshift @source
           path
         end
 
@@ -35,13 +35,15 @@ def traverse(graph, vertex)
           queue = ::Queue.new
           @visited[vertex] = true
           queue.enq vertex
+          yield vertex if block_given?
           until queue.empty?
             next_vertex = queue.deq
-            graph.adjacency(next_vertex).each do |neighbour_vertex|
+            graph.adjacency_list(next_vertex).each do |neighbour_vertex|
               next if visited? neighbour_vertex
               @edge_to[neighbour_vertex] = next_vertex
               @visited[neighbour_vertex] = true
               queue.enq neighbour_vertex
+              yield neighbour_vertex if block_given?
             end
           end
         end

lib/algorithmable/graphs/traversals/depth_first.rb

@@ -4,11 +4,11 @@ module Traversals
       class DepthFirst
         include Algorithmable::Graphs::Traversals::Errors
 
-        def initialize(graph, source)
+        def initialize(graph, source, &f)
           @visited = []
           @edge_to = []
           @source = source
-          traverse graph, source
+          traverse graph, source, &f
         end
 
         def visited?(vertex)
@@ -20,21 +20,22 @@ def path_to(vertex)
           path = []
           finish = vertex
           while finish != @source
-            path.push finish
+            path.unshift finish
             finish = @edge_to[finish]
           end
-          path.push @source
+          path.unshift @source
           path
         end
 
         private
 
-        def traverse(graph, vertex)
+        def traverse(graph, vertex, &f)
           @visited[vertex] = true
-          graph.adjacency(vertex).each do |neighbour_vertex|
+          yield vertex if block_given?
+          graph.adjacency_list(vertex).each do |neighbour_vertex|
             unless visited? neighbour_vertex
               @edge_to[neighbour_vertex] = vertex
-              traverse graph, neighbour_vertex
+              traverse graph, neighbour_vertex, &f
             end
           end
         end

lib/algorithmable/graphs/traversals/topological_sort.rb

@@ -0,0 +1,31 @@
+module Algorithmable
+  module Graphs
+    module Traversals
+      class TopologicalSort
+        include Algorithmable::Graphs::Traversals::Errors
+
+        def self.sort(graph, &f)
+          stack = []
+          visited = []
+          graph.edges.each_index do |i|
+            next if visited[i]
+            do_sort(graph, i, stack, visited, &f)
+          end
+          stack
+        end
+
+        def self.do_sort(graph, vertex, stack, visited, &f)
+          visited[vertex] = true
+          graph.adjacency_list(vertex).each do |edge|
+            next if visited[edge.to]
+            do_sort graph, edge.to, stack, visited, &f
+          end
+          yield vertex if block_given?
+          stack.unshift vertex
+        end
+
+        private_class_method :do_sort
+      end
+    end
+  end
+end

lib/algorithmable/graphs/undirected.rb

@@ -6,20 +6,20 @@ class Undirected
       def initialize(vertices = 0)
         @vertices = vertices
         @edges = 0
-        @adj = []
-        @vertices.times { |i| @adj[i] = [] }
+        @adjacency_list = []
+        @vertices.times { |i| @adjacency_list[i] = [] }
       end
 
       def add_edge(left_vertex, right_vertex)
-        @adj[left_vertex] ||= []
-        @adj[right_vertex] ||= []
-        @adj[left_vertex].push right_vertex
-        @adj[right_vertex].push left_vertex
+        @adjacency_list[left_vertex] ||= []
+        @adjacency_list[right_vertex] ||= []
+        @adjacency_list[left_vertex].push right_vertex
+        @adjacency_list[right_vertex].push left_vertex
         @edges = @edges.next
       end
 
-      def adjacency(vertex)
-        @adj[vertex]
+      def adjacency_list(vertex)
+        @adjacency_list[vertex]
       end
 
       def valid_vertex?(vertex)
@@ -28,14 +28,14 @@ def valid_vertex?(vertex)
 
       def degree(vertex)
         fail "Vertex #{vertex} is not valid." unless valid_vertex?(vertex)
-        adjacency(vertex).size
+        adjacency_list(vertex).size
       end
 
       def to_s
         data = ''
         @vertices.times do |vertex|
           data += "( #{vertex} => "
-          @adj[vertex].each do |neighbor|
+          @adjacency_list[vertex].each do |neighbor|
             data += "#{neighbor} "
           end
           data += ') '

lib/algorithmable/searches.rb

@@ -1,14 +1,9 @@
 module Algorithmable
   module Searches
     autoload :BinarySearch, 'algorithmable/search/binary_search'
-    autoload :BinarySearchTree, 'algorithmable/search/binary_search_tree'
 
     def binary_search(element, collection)
       BinarySearch.lookup(element, collection)
     end
-
-    def new_binary_search_tree(key_type, value_type)
-      BinarySearchTree.new key_type, value_type
-    end
   end
 end

lib/algorithmable/sort/bubble.rb

@@ -6,12 +6,14 @@ class Bubble
       # Time О(N^2), stable and slow
       # Space О(N)
       #
+      # Optimized implementation of Bubble sort
+      #
       def self.sort(collection)
         length = collection.length - 1
         loop do
           swapped = false
           0.upto(length).each do |i|
-            if 1 == (collection[i] <=> collection[i + 1])
+            if 1 == (collection[i] <=> collection[i + 1]) #nil safe comparison
               swap(collection, i)
               swapped = true
             end