Implement graph algorithm: Depth-First Search, (for adjacency matrix based graph) (issue #19)

README.md

@@ -131,6 +131,30 @@ graph.add_edge(3, 5, 4) # edge from vertex 3 to vertex 5 with weight 4
 puts graph
 ```
 
+## Algorithms usage
+
+```ruby
+
+# initializes Algorithms object
+alg = Algorithms.new
+
+# matrix example
+matrix = AdjMatrixGraph.new
+matrixSrc = [[0, 0, 2],
+             [2, 0, 0],
+             [0, 2, 0]]
+matrix.load_from_array(matrixSrc)
+
+# lambda which will be used for each vertex
+my_print = lambda { |n| print(n) }
+
+# matrix_DFS call
+alg.matrix_DFS(matrix, my_print)
+# 0 2 1 
+
+```
+
+
 ## Data formats
 
 ```

lib/visual_graphs/algorithms.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+module VisualGraphs
+  # class with different algorithms for graphs
+  class Algorithms
+
+    # Depth-First Search, (for adjacency matrix based graph)
+    def matrix_DFS(graph_matrix, vertexAction)
+
+      msg = 'argument must be of AdjMatrixGraph type'
+      raise AdjacencyMatrixError, msg unless graph_matrix.is_a?(AdjMatrixGraph)
+
+      matrix = graph_matrix.adjacency_matrix
+      initial_index = 0
+
+      visited = []
+      node_stack = [initial_index]
+      loop do
+        curr_node = node_stack.shift
+
+        visited.append(curr_node)
+        return false if curr_node == nil
+        return true if curr_node == matrix.length
+
+        vertexAction.call(curr_node)
+
+        children = (0..matrix.length-1).to_a.select do |i|
+          # do not process loops
+          next if curr_node == i
+          next if visited.find{|v| v == i} != nil
+
+          matrix[curr_node][i] != 0
+        end
+
+        node_stack = node_stack + children
+      end
+    end
+  end
+end
+

test/algorithms_test.rb

@@ -0,0 +1,85 @@
+# frozen_string_literal: true
+
+require "./test/test_helper"
+require './lib/visual_graphs/algorithms'
+require './lib/visual_graphs/adjacency_matrix_graph'
+
+class AlgorithmTest < Minitest::Test
+  include VisualGraphs
+
+  def test_exists_matrix_DFS_method
+      assert Algorithms.methods.size > 0
+  end
+
+  def test_matrix_DFS_does_not_accept_invalid_data
+    alg = Algorithms.new
+
+    exception = assert_raises AdjacencyMatrixError do
+      my_print = lambda { |n| print(n ) }
+      alg.matrix_DFS(5, my_print)
+    end
+    assert_equal 'argument must be of AdjMatrixGraph type', exception.message
+
+    exception = assert_raises AdjacencyMatrixError do
+      my_print = lambda { |n| print(n ) }
+      alg.matrix_DFS([1, 2, 3], my_print)
+    end
+    assert_equal 'argument must be of AdjMatrixGraph type', exception.message
+
+    exception = assert_raises AdjacencyMatrixError do
+      my_print = lambda { |n| print(n ) }
+      alg.matrix_DFS("it's joke", my_print)
+    end
+    assert_equal 'argument must be of AdjMatrixGraph type', exception.message
+  end
+
+  def test_matrix_DFS_correct_work_size2
+    alg = Algorithms.new
+
+    matrix = AdjMatrixGraph.new
+    matrixSrc = [[2, 3], [0, 1]]
+    matrix.load_from_array(matrixSrc)
+
+    traversed_vertices = []
+    traverse = lambda { |n| traversed_vertices.append(n) }
+    alg.matrix_DFS(matrix, traverse)
+
+    assert_equal traversed_vertices, [0, 1]
+  end
+
+
+  def test_matrix_DFS_correct_work_size5
+    alg = Algorithms.new
+
+    matrix = AdjMatrixGraph.new
+    matrixSrc = [[0, 1, 1, 0, 0],
+                 [0, 0, 0, 0, 0],
+                 [0, 0, 0, 1, 1],
+                 [0, 0, 0, 0, 0],
+                 [0, 0, 0, 0, 0]]
+    matrix.load_from_array(matrixSrc)
+
+    traversed_vertices = []
+    traverse = lambda { |n| traversed_vertices.append(n) }
+    alg.matrix_DFS(matrix, traverse)
+
+    assert_equal traversed_vertices, [0, 1, 2, 3, 4]
+  end
+
+  def test_matrix_DFS_correct_work_size3
+    alg = Algorithms.new
+
+    matrix = AdjMatrixGraph.new
+    matrixSrc = [[0, 0, 2],
+                 [2, 0, 0],
+                 [0, 2, 0]]
+    matrix.load_from_array(matrixSrc)
+
+    traversed_vertices = []
+    traverse = lambda { |n| traversed_vertices.append(n) }
+
+    alg.matrix_DFS(matrix, traverse)
+
+    assert_equal traversed_vertices, [0, 2, 1]
+  end
+end

test/resources/test_min_heap.txt

@@ -0,0 +1,7 @@
+printing min heap:
+nil
+Vertex <key: 5 value: 5 color: black name: >
+Vertex <key: 6 value: 6 color: black name: >
+Vertex <key: 8 value: 8 color: black name: >
+Vertex <key: 12 value: 12 color: black name: >
+Vertex <key: 7 value: 7 color: black name: >