message: Update k-empty-slots.py
diff: # Time: O(n)
  # Space: O(n)
  +# There is a garden with N slots. In each slot, there is a flower.
  +# The N flowers will bloom one by one in N days. In each day,
  +# there will be exactly one flower blooming and it will be in the status of blooming since then.
  +#
  +# Given an array flowers consists of number from 1 to N.
  +# Each number in the array represents the place where the flower will open in that day.
  +#
  +# For example, flowers[i] = x means that the unique flower that blooms at day i
  +# will be at position x, where i and x will be in the range from 1 to N.
  +#
  +# Also given an integer k, you need to output in which day there exists two flowers
  +# in the status of blooming, and also the number of flowers between them is k and
  +# these flowers are not blooming.
  +#
  +# If there isn't such day, output -1.
  +#
  +# Example 1:
  +# Input:
  +# flowers: [1,3,2]
  +# k: 1
  +# Output: 2
  +# Explanation: In the second day, the first and the third flower have become blooming.
  +#
  +# Example 2:
  +# Input:
  +# flowers: [1,2,3]
  +# k: 1
  +# Output: -1
  +# Note:
  +# The given array will be in the range [1, 20000].
  +
  class Solution(object):
  def kEmptySlots(self, flowers, k):
  """
  