old_contents: # Time:  O(1)
  # Space: O(1)
  
  class Solution(object):
      def flipLights(self, n, m):
          """
          :type n: int
          :type m: int
          :rtype: int
          """
          if m == 0:            return 1
          if n == 1:            return 2
          if m == 1 and n == 2: return 3
          if m == 1 or  n == 2: return 4
          if m == 2:            return 7
          return 8
  
new_contents: # Time:  O(1)
  # Space: O(1)
  
  # There is a room with n lights which are turned on initially and 4 buttons on the wall.
  # After performing exactly m unknown operations towards buttons,
  # you need to return how many different kinds of status of the n lights could be.
  #
  # Suppose n lights are labeled as number [1, 2, 3 ..., n], function of these 4 buttons are given below:
  #   1. Flip all the lights.
  #   3. Flip lights with even numbers.
  #   3. Flip lights with odd numbers.
  #   4. Flip lights with (3k + 1) numbers, k = 0, 1, 2, ...
  #
  # Example 1:
  # Input: n = 1, m = 1.
  # Output: 2
  # Explanation: Status can be: [on], [off]
  # Example 2:
  # Input: n = 2, m = 1.
  # Output: 3
  # Explanation: Status can be: [on, off], [off, on], [off, off]
  # Example 3:
  # Input: n = 3, m = 1.
  # Output: 4
  # Explanation: Status can be: [off, on, off], [on, off, on], [off, off, off], [off, on, on].
  # Note: n and m both fit in range [0, 1000].
      
  class Solution(object):
      def flipLights(self, n, m):
          """
          :type n: int
          :type m: int
          :rtype: int
          """
          if m == 0:            return 1
          if n == 1:            return 2
          if m == 1 and n == 2: return 3
          if m == 1 or  n == 2: return 4
          if m == 2:            return 7
          return 8
  
subject: Update bulb-switcher-ii.py