ruby 堆排序

[ruby]代码库

def heapify(a, idx, size)
  left_idx = 2 * idx + 1
  right_idx = 2 * idx + 2
  bigger_idx = idx
  bigger_idx = left_idx if left_idx < size && a[left_idx] > a[idx]
  bigger_idx = right_idx if right_idx < size && a[right_idx] > a[bigger_idx]
  if bigger_idx != idx
    a[idx], a[bigger_idx] = a[bigger_idx], a[idx]
    heapify(a, bigger_idx, size)
  end
end

def build_heap(a)
  last_parent_idx = a.length / 2 - 1
  i = last_parent_idx
  while i >= 0
    heapify(a, i, a.size)
    i = i - 1
  end
end

def heap_sort(a)
  return a if a.size <= 1
  size = a.size
  build_heap(a)
  while size > 0
    a[0], a[size-1] = a[size-1], a[0]
    size = size - 1
    heapify(a, 0, size)
  end
  return a
end