Question

我正在进行的教程有以下程序

# This program calculates the Fibonacci sequence
a = 0
b = 1
count = 0
max_count = 20
while count < max_count:
    count = count + 1
    old_a = a    # we need to keep track of a since we change it
    print(old_a,end=" ")   # Notice the magic end=" " in the print function arguments that
                           # keeps it from creating a new line
    a = b
    b = old_a + b
print() # gets a new (empty) line

代码很完美。但是，我无法弄清楚序列是如何计算的。如何更改值以创建序列？

Answer 1

如果删除所有无关的代码，那将更有意义：

while count < max_count:
    old_a = a
    a = b
    b = old_a + b

old_a可能让您感到困惑。这是写这篇文章的漫长道路：

a, b = b, a + b

将a与b和（{同时），b与a + b进行互换。请注意，与写入相同：

a = b
b = a + b

因为当您重新定义b时，a已经保留了新值，等于b。

我也会通过在纸上书写来手动完成代码。

Answer 2

此代码可以正常工作：

a, b = 0, 1
for _ in range(20):
        print a
        a, b = b, a+b

Python中的Fibonacci序列逻辑

2 个答案: