Add min max divide and conquer in Ruby

Author: davide-almeida

README.md

@@ -1310,8 +1310,8 @@ In order to achieve greater coverage and encourage more people to contribute to
                 </a>
             </td>
             <td> <!-- Ruby -->
-                <a href="./CONTRIBUTING.md">
-                    <img align="center" height="25" src="./logos/github.svg" />
+                <a href="./src/ruby/min_max_dc.rb">
+                    <img align="center" height="25" src="./logos/ruby.svg" />
                 </a>
             </td>
             <td> <!-- JavaScript -->

src/ruby/min_max_dc.rb

@@ -0,0 +1,22 @@
+require 'test/unit/assertions'
+include Test::Unit::Assertions
+
+def min_max_dc(vector, start_index, end_index)
+  if start_index == end_index
+    return [vector[start_index], vector[start_index]]
+  end
+
+  middle = (start_index + end_index) / 2
+  left_min, left_max = min_max_dc(vector, start_index, middle)
+  right_min, right_max = min_max_dc(vector, middle + 1, end_index)
+
+  min = left_min < right_min ? left_min : right_min
+  max = left_max > right_max ? left_max : right_max
+
+  [min, max]
+end
+
+assert_equal([1, 5], min_max_dc([1, 2, 3, 4, 5], 0, 4))
+assert_equal([14, 55], min_max_dc([13, 55, 42, 14, 15], 1, 3))
+assert_equal([13, 13], min_max_dc([13, 55, 42, 14, 15], 0, 0))
+assert_equal([14, 15], min_max_dc([13, 55, 42, 14, 15], 3, 4))