message: Update flood-fill.py
diff: -# Time: O(r * c)
  -# Space: O(r * c)
  +# Time: O(m * n)
  +# Space: O(m * n)
  # An image is represented by a 2-D array of integers,
  # each integer representing the pixel value of the image (from 0 to 65535).
  @@ -41,7 +41,7 @@ class Solution(object):
  """
  directions = [(0, -1), (0, 1), (-1, 0), (1, 0)]
  - def dfs(image, r, c, color):
  + def dfs(image, r, c, newColor, color):
  if not (0 <= r < len(image) and \
  0 <= c < len(image[0]) and \
  image[r][c] == color):
  @@ -49,9 +49,9 @@ class Solution(object):
  image[r][c] = newColor
  for d in directions:
  - dfs(image, r+d[0], c+d[1], color)
  + dfs(image, r+d[0], c+d[1], newColor, color)
  color = image[sr][sc]
  if color == newColor: return image
  - dfs(image, sr, sc, color)
  + dfs(image, sr, sc, newColor, color)
  return image
  