解释：
菲波那切数列本质

class Solution:
    def rectCover(self, number):
        # write code here
        if number == 0:
            return 0
        if number == 1:
            return 1
        if number == 2:
            return 2

        fOne = 1
        fTwo = 2
        for i in range(3,number+1):
            fN = fTwo + fOne
            fOne = fTwo
            fTwo = fN
        return  fN