We have two types of tiles: a 2x1 domino shape, and an "L" tromino shape. These shapes may be rotated.
XX  <- domino
XX  <- "L" tromino
X
Given N, how many ways are there to tile a 2 x N board? Return your answer modulo 10^9 + 7.
(In a tiling, every square must be covered by a tile. Two tilings are different if and only if there are two 4-directionally adjacent cells on the board such that exactly one of the tilings has both squares occupied by a tile.)
Example:
Input: 3
Output: 5
Explanation: 
The five different ways are listed below, different letters indicates different tiles:
XYZ XXZ XYY XXY XYY
XYZ YYZ XZZ XYY XXY
Note:
       N  will be in range [1, 1000].
class Solution:
     def isIdealPermutation(self, A):
         """
         :type A: List[int]
         :rtype: bool
         """
         return all(abs(v-i)<=1 for i,v in enumerate(A)) #有意思 其中的原理更有意思
class Solution:
     def isIdealPermutation(self, A):
         """
         :type A: List[int]
         :rtype: bool
         """
         return all(abs(v-i)<=1 for i,v in enumerate(A)) #有意思 其中的原理更有意思