剑指Offer(十)：矩形覆盖

解法1：就是一个斐波那契数列！

class Solution:
    def rectCover(self, number):
        # write code here
        if number <= 3:
            return number
        first,second,third = 1,2,0
        for i in range(3,number+1):
            third = first+second
            first = second
            second = third
        return third