Python Exercise Example 6

Python 100 Li

Title: Number of Fibonacci sequence.

Program Analysis: Fibonacci number (Fibonacci sequence), also known as golden columns, referring to a number of columns: 0,1,1,2,3,5,8,13,21,34, .......

Mathematically, the fee Fibonacci series is a recursive way to define:

F0 = 0     (n=0)
F1 = 1    (n=1)
Fn = F[n-1]+ F[n-2](n=>2)

Source Code:

method one

#!/usr/bin/python
# -*- coding: UTF-8 -*-

def fib(n):
	a,b = 1,1
	for i in range(n-1):
		a,b = b,a+b
	return a

# 输出了第10个斐波那契数列
print fib(10)

Method Two

#!/usr/bin/python
# -*- coding: UTF-8 -*-

# 使用递归
def fib(n):
	if n==1 or n==2:
		return 1
	return fib(n-1)+fib(n-2)

# 输出了第10个斐波那契数列
print fib(10)

Examples of output above the first 10 Fibonacci number, the result is:

55

Method Three

If you need to output a specified number of Fibonacci number, you can use the following code:

#!/usr/bin/python
# -*- coding: UTF-8 -*-

def fib(n):
    if n == 1:
        return [1]
    if n == 2:
        return [1, 1]
    fibs = [1, 1]
    for i in range(2, n):
        fibs.append(fibs[-1] + fibs[-2])
    return fibs

# 输出前 10 个斐波那契数列
print fib(10) 

Run the above program output is:

[1, 1, 2, 3, 5, 8, 13, 21, 34, 55]

Python 100 Li