一个岛上有一对神秘的小兔子,一个月后它们会长成一对大兔子,再一个月后他们会生下一对小兔子,必定是一公一母(即:第一个月的月末会有一对大兔子,第二个月月末会有一对大兔子和一对小兔子),我们定义在第x个月月末时的兔子对数为f(x),请问f(8) = 1
f(8),计算量不大...列表统计即可
兔子数 | 月份 |
---|---|
1对大 | 1 |
1对大,1对小 | 2 |
2对大,1对小 | 3 |
3对大,2对小 | 4 |
5对大,3对小 | 5 |
8对大,5对小 | 6 |
13对大,8对小 | 7 |
21对大,13对小 | 8 |
2, 2m -> 2 + 2 => n,2m -> 2n => n,m -> n1 n1,m -> 2n m = 1 => n,m -> n1 1: n1 0: 0 m = 2 => n1,m -> n 1: n1 0: n m = 3 => n1,m -> n => n,m -> n1 1: n1 + n1 = f_m_n1(m-1) + f_m_n(m-1) 0: n = f_m_n1(m-1) ... f_m_n1(m) = f_m_n1(m-1) + f_m_n(m-1); f_m_n(m) = f_m_n1(m-1) f(x) = f_m_n1(x) + f_m_n(x) = f(x-1) + f(x-2) f(1) = 1 f(0) = 1 f(2) = f(1) + f(0) = 2 f(3) = f(2) + f(1) = 2 + 1 = 3 f(4) = f(3) + f(2) = 3 + 2 = 5 f(5) = f(4) + f(3) = 5 + 3 = 8 f(6) = f(5) + f(4) = 8 + 5 = 13 f(7) = f(6) + f(5) = 13 + 8 = 21 f(8) = f(7) + f(6) = 21 + 13 = 34