Add merge sort

Sorting/merge_sort.rb

@@ -0,0 +1,32 @@
+def merge_sort(array)
+  return array if array.length <= 1
+  mid = array.length / 2
+  first_array = array.slice(0..mid - 1)
+  second_array = array.slice(mid..-1)
+
+  first_array = merge_sort first_array
+  second_array = merge_sort second_array
+
+  # merge
+  result = []
+  until first_array.empty? and second_array.empty?
+    if first_array.empty?
+      result.concat(second_array)
+      second_array.clear
+    elsif second_array.empty?
+      result.concat(first_array)
+      first_array.clear
+    else
+      if first_array.first < second_array.first
+        result << first_array.shift
+      else
+        result << second_array.shift
+      end
+    end
+  end
+  result
+end
+
+puts "Enter a list of numbers seprated by space"
+list = gets
+print merge_sort list.split(" ").map(&:to_i)