Added Quick Sort in Ruby

Ruby/QuickSort.rb

@@ -0,0 +1,44 @@
+#!/usr/bin/env ruby
+
+# Run it from a terminal as a ruby script, with space separated numbers:
+# ruby QuickSort 23 12 3 99 129 482 12
+
+array = ARGV
+array.map!(&:to_i)
+puts 'Your unsorted numbers'
+p array
+
+# Quick Sort algorithm
+class QuickSort
+  class << self
+    def sort(array, first, last)
+      if first < last
+        partitionIndex = partition(array, first, last)
+        sort(array, first, partitionIndex-1)
+        sort(array, partitionIndex+1, last)
+      end
+      return array
+    end
+
+    private
+
+    def partition(array, first, last)
+      pivot = array[last] # Pivot
+      partitionIndex = first # Partition index
+      for i in first...last
+        if array[i] <= pivot
+          array[i], array[partitionIndex] = array[partitionIndex], array[i] # Swapping
+          partitionIndex += 1
+        end
+      end
+      i += 1
+
+      array[i], array[partitionIndex] = array[partitionIndex], array[i] # Swapping
+
+      return partitionIndex
+    end
+  end
+end
+
+puts "\nNumbers sorted:"
+p QuickSort.sort(array, 0, array.size-1)