Another update from ingydotnet^djgoku

Task/Sorting-algorithms-Quicksort/Ruby/sorting-algorithms-quicksort-1.rb

@@ -1,9 +1,8 @@
 class Array
   def quick_sort
     return self if length <= 1
-    pivot = sample
-    find_all { |i| i <  pivot }.quick_sort +
-      find_all { |i| i == pivot } +
-      find_all { |i| i >  pivot }.quick_sort
+    pivot = self[0]
+    less, greatereq = self[1..-1].partition { |x| x < pivot }
+    less.quick_sort + [pivot] + greatereq.quick_sort
   end
 end

Task/Sorting-algorithms-Quicksort/Ruby/sorting-algorithms-quicksort-2.rb

@@ -1,8 +1,9 @@
 class Array
   def quick_sort
     return self if length <= 1
-    pivot = self[0]
-    less, greatereq = self[1..-1].partition { |x| x < pivot }
-    less.quick_sort + [pivot] + greatereq.quick_sort
+    pivot = sample
+    group = group_by{ |x| x <=> pivot }
+    group.default = []
+    group[-1].quick_sort + group[0] + group[1].quick_sort
   end
 end

Task/Sorting-algorithms-Quicksort/Ruby/sorting-algorithms-quicksort-3.rb

@@ -1,9 +1,6 @@
 class Array
   def quick_sort
-    return self if length <= 1
-    pivot = sample
-    group = group_by{ |x| x <=> pivot }
-    group.default = []
-    group[-1].quick_sort + group[0] + group[1].quick_sort
+    h, *t = self
+    h ? t.partition { |e| e < h }.inject { |l, r| l.quick_sort + [h] + r.quick_sort } : []
   end
 end