由 --- 於 星期四 九月 21, 2017 3:37 pm
F(12)=?
(1)when the next is A2, he should sit on 3, the condition become F(11)
(2)when the next is not A2 but An, he should sit on n, the condition become
F(11)
So,F(12)=2*F(11)
so do F(11)=2*F(10)
...
F(2)=1
so, F(12)=2^10=1024