Data commit

Task/Sorting-algorithms-Heapsort/Ruby/sorting-algorithms-heapsort.rb

@@ -0,0 +1,34 @@
+class Array
+  def heapsort
+    self.dup.heapsort!
+  end
+
+  def heapsort!
+    # in pseudo-code, heapify only called once, so inline it here
+    ((length - 2) / 2).downto(0) {|start| siftdown(start, length - 1)}
+
+    # "end" is a ruby keyword
+    (length - 1).downto(1) do |end_|
+      self[end_], self[0] = self[0], self[end_]
+      siftdown(0, end_ - 1)
+    end
+    self
+  end
+
+  def siftdown(start, end_)
+    root = start
+    loop do
+      child = root * 2 + 1
+      break if child > end_
+      if child + 1 <= end_ and self[child] < self[child + 1]
+        child += 1
+      end
+      if self[root] < self[child]
+        self[root], self[child] = self[child], self[root]
+        root = child
+      else
+        break
+      end
+    end
+  end
+end