message: Update count-number-of-ways-to-place-houses.py
diff: -# Time: O(n)
  +# Time: O(logn)
  # Space: O(1)
  +import itertools
  +
  +
  # matrix exponentiation
  class Solution(object):
  def countHousePlacements(self, n):
  @@ -38,6 +41,6 @@ class Solution2(object):
  """
  MOD = 10**9+7
  prev, curr = 0, 1
  - for i in xrange(n+1):
  + for _ in xrange(n+1):
  prev, curr = curr, (prev+curr)%MOD
  return pow(curr, 2, MOD)
  