ruby selection sort (#67)

src/ruby/sort_selection_sort.rb

@@ -0,0 +1,67 @@
+# frozen_string_literal: true
+
+#####################
+# sort script start #
+#####################
+
+# selection sort!
+#
+# docs: https://en.wikipedia.org/wiki/Selection_sort
+#
+# Selection sort looks through every element an input list, and finds the
+# smallest element. That element is then appended to the end of an output list.
+# When it reaches the end of the input list, all of the output elements will
+# be sorted.
+
+def do_sorting(input_list)
+  selection_sort(input_list)
+end
+
+def selection_sort(input_list)
+  sorted_elements = []
+  unsorted_elements = input_list
+
+  (0..unsorted_elements.length).each do |_|
+    # puts '--- (0..unsorted_elements.length).each do |_| ---'
+    # puts "unsorted_elements #{unsorted_elements}"
+    # puts "sorted_elements #{sorted_elements}"
+
+    smallest_index = find_smallest_index(unsorted_elements)
+    smallest_element = unsorted_elements[smallest_index]
+    sorted_elements.append(smallest_element)
+    # ruby `pop` DOES NOT work the same as python `pop`
+    # for python `pop` in ruby, use `delete_at`
+    unsorted_elements.delete_at(smallest_index)
+
+    # puts "smallest_index #{smallest_index}"
+    # puts "smallest_element #{smallest_element}"
+    # puts "unsorted_elements #{unsorted_elements}"
+    # puts "sorted_elements #{sorted_elements}"
+  end
+
+  sorted_elements
+end
+
+def find_smallest_index(input_list)
+  smallest_index = 0
+
+  input_list.each_with_index do |element, index|
+    smallest_index = index if element < input_list[smallest_index]
+  end
+
+  smallest_index
+end
+
+###################
+# sort script end #
+###################
+
+# 👇🏽 copy pasted helpers
+
+input_file_path = ENV['INPUT_PATH']
+input_file = File.readlines(input_file_path)
+
+sorted_data = do_sorting(input_file)
+
+output_file_path = ENV['OUTPUT_PATH']
+File.open(output_file_path, 'wb') { |f| f.write(sorted_data.join('')) }