嵌套循环斐波那契数列

Question

我正在尝试编写一个程序，要求用户输入一个数字。然后我需要验证它是否在 fib 序列中

代码：

# asking the user to input number
number = int(input("Enter a number: "))

# creating empty list to be filled
sequence = [0, 1]

x = -2
y = -1


# append items to list
for i in range(number):
    x+=2
    y+=2
# this code will be executed 'length' times
    sequence.append(x+y)

# This should be somewhere in the loop: 
if number in sequence:
    print("The number is in the Fibonacci sequence")
else:
    print("The number is not in the Fibonacci sequence")

预期输出：

斐波那契数列 = 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, ….

Enter a number: 5
>>> The number is in the Fibonacci sequence

Answer 1

序列没有位置 x 或 y。您附加到序列的行应显示为 sequence.append(x+y)

Answer 2

可能是我想的太简单了，但是根据你的问题，好像是给你提供了一个斐波那契数列。如果是这种情况，您可以只使用 in，即

x = 5 # this will be user's input
fib = [0,1,1,2,3,5,8,13,21,34]
if x in fib:
    print('Number is in sequence')
else:
    print('Number is not in sequence')

如果您必须生成自己的斐波那契数列，那么您可能需要考虑使用递归。

Answer 3

您需要进行一些迭代（或递归）才能找到斐波那契数列。这是使用 while 循环执行此操作的一种方法：

number = int(input("Enter a number: "))

sequence = [0, 1]

i= 0
while True:
    new_item = sequence[i] + sequence[i+1]
    if new_item == number or number in [0,1]:
        print("The number is in the Fibonacci sequence")
        break
    elif new_item > number:
        print("The number is not in the Fibonacci sequence")
        break
    sequence.append(new_item)
    i+=1

请注意，您将迭代直到斐波那契数列中的新项目大于或等于用户输入的数字。

Answer 4

或者你可以只计算斐波那契数

def fibo(n):
    p = (1+5**.5)/2
    q = (1-5**.5)/2
    return int(1/5**.5*(p**n-q**n))

def fiba(num):
     count = 0
     while fibo(count) <= num:
             if fibo(count) == num:
                     return "YES!"
             count += 1
     return "NO!"

Answer 5

一种方法是将 fibonacci 分解为一个生成器，然后迭代该生成器直到 >= number，例如：

def fib():
    a, b = 0, 1
    while True:
        yield a
        a, b = b, a+b

In []    
number = 5 # int(input("Enter a number: "))

for f in fib():
    if f >= number:
        break

if number == f:
    print("The number is in the Fibonacci sequence")
else:
    print("The number is not in the Fibonacci sequence")

Out[]:
The number is in the Fibonacci sequence

你可以用itertools.takewhile代替for循环，例如：

import itertools as it
from collections import deque

f = deque(it.takewhile(lambda n: n <= number, fib()), maxlen=1).pop()

...

嵌套循环斐波那契数列

Nested Loops Fibonacci Sequence

python

nested-loops