message: Update take-gifts-from-the-richest-pile.py
diff: # Time: O(n + klogn)
  -# Space: O(n)
  +# Space: O(1)
  import heapq
  @@ -12,9 +12,10 @@ class Solution(object):
  :type k: int
  :rtype: int
  """
  - max_heap = [-x for x in gifts]
  - heapq.heapify(max_heap)
  + for i, x in enumerate(gifts):
  + gifts[i] = -x
  + heapq.heapify(gifts)
  for _ in xrange(k):
  - x = heapq.heappop(max_heap)
  - heapq.heappush(max_heap, -int((-x)**0.5))
  - return -sum(max_heap)
  + x = heapq.heappop(gifts)
  + heapq.heappush(gifts, -int((-x)**0.5))
  + return -sum(gifts)
  