Dijkstra's algorithm

lib/visual_graphs.rb

@@ -17,6 +17,9 @@ class WrongParamsForWeightedGraphInit < StandardError; end
   # error which occurs in case of accessing non-existent files
   class FileDoesNotExist < StandardError; end
 
+  #error for wrong inner values in algorithm
+  class WrongParamsForAlgorithm; end
+
   # errors connected with defining of adjacency matrix
   class AdjacencyMatrixError < StandardError
     def initialize(msg = '', exception_type = '')

lib/visual_graphs/algorithms.rb

@@ -0,0 +1,79 @@
+require_relative 'weighted_graph'
+
+module  VisualGraphs
+  #Algorihtms class for Visual Graph
+  class Algorithms
+
+    INF = 1000000000
+
+    def init
+      #infinity value
+    end
+
+
+    def check_graph_for_dijkstra(wh_gr, start)
+
+      #Check class of input value
+      unless wh_gr.is_a?(WeightedGraph) or all_weight_positive(wh_gr)
+        raise WrongParamsForAlgorithm
+      end
+
+      unless wh_gr.adjacency_list.has_key?(start)
+        raise WrongParamsForAlgorithm
+      end
+
+    end
+
+    def all_weight_positive(wh_gr)
+      wh_gr.edges.each{ |t|
+        t.each do
+          if t.is_a? Array and t.length == 2 and t[1] <= 0
+            return false
+          end
+        end
+      }
+      true
+    end
+
+    #Dijkstra alg
+    # return distance from spec vertex for others
+    def dijkstra(wh_gr, start)
+
+      check_graph_for_dijkstra(wh_gr, start)
+
+      #Convert to hash
+      number_of_element = wh_gr.adjacency_list.length
+      dist = Hash.new(INF)
+      flags = Hash.new(false)
+
+      dist[start] = 0
+
+      number_of_element.times do
+        v = find_uncheck_min(wh_gr, flags, dist)
+
+        flags[v] = true
+
+        wh_gr.adjacency_list[v].each{ |g|
+          if dist[v] + g[1] < dist[g[0]]
+            dist[g[0]] = dist[v] + g[1]
+          end
+        }
+      end
+      dist
+
+    end
+
+    def find_uncheck_min(wh_gr, flags, dist)
+      v = "-1"
+      wh_gr.vertices.each { |j|
+        if not flags[j] and (v == -1 or dist[j] < dist[v])
+          v = j
+        end
+      }
+      v
+    end
+
+  end
+end
+
+

test/algorithms_test.rb

@@ -0,0 +1,31 @@
+require 'minitest/autorun'
+require './lib/visual_graphs/algorithms'
+require './lib/visual_graphs/weighted_graph'
+
+module VisualGraphs
+  class AlgorithmsTest < Minitest::Test
+    def setup
+      @filepathToWeighted = 'test/resources/test_weighted_graph.json'
+      @filepath = 'test/resources/test_data.json'
+    end
+
+
+    def basic_test_Dijkstra
+      graph = WeightedGraph.load_from_json(@filepathToWeighted)
+      dist = Algorithms.dijkstra(graph, "1")
+      assert_equal [0, 3, 5], dist, 'wrong dist'
+    end
+
+    def wrong_graph_Dijkstra
+      assert_raises WrongParamsForAlgorithm do
+        graph = Graph.load_from_json(@filepath)
+        Algorithms.dijkstra(graph, "1")
+      end
+
+      assert_raises WrongParamsForAlgorithm do
+        graph = WeightedGraph.load_from_json(@filepathToWeighted)
+        Algorithms.dijkstra(graph, "120")
+      end
+    end
+  end
+end