斐波那契数列
斐波那契数列(Fibonacci sequence)的定义:斐波那契数列指的是这样一个数列 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233,377,610,987,1597,2584,4181,6765,10946,17711,28657,46368…,这个数列从第3项开始,每一项都等于前两项之和。
在数学上,斐波纳契数列以如下被以递归的方法定义:F(0)=0,F(1)=1, F(n)=F(n-1)+F(n-2)(n>=2,n∈N*)。
方法一:普通版
def create_num(all_num):
a, b = 0, 1
current_num = 0
while current_num <all_num:
print(a)
a, b = b, a+b
current_num += 1
create_num(10)
方法二:递归函数
def feibo(n):
if n == 1:
return 0
if n == 2:
return 1
return feibo(n-1) + feibo(n-2)
for i in range(10):
print(feibo(i+1))
方法三:迭代器
class Fibonacci(object):
def __init__(self, all_num):
self.all_num = all_num
self.current_num = 0
self.a = 0
self.b = 1
def __iter__(self):
return self
def __next__(self):
if self.current_num < self.all_num:
ret = self.a
self.a, self.b = self.b, self.a+self.b
self.current_num += 1
return ret
else:
raise StopIteration
fibo = Fibonacci(10)
for num in fibo:
print(num)
结果:
0
1
1
2
3
5
8
13
21
34