python学习--递归实例

#!/usr/bin/env python3
# -*- coding: utf-8

'''循环(loop) 迭代(iterate) 递归(recursion) 遍历(traversal)
   斐波那契数列
'''
a, b = 0, 1
for i in range(4):
    a, b = b, a+b

print(a)

def fibs(n):
    '''这是一个Fibonacci 序列
    '''
    result = [0, 1]
    for i in range(n-2):
        result.append(result[-2] + result[-1])
    return result

if __name__ == "__main__":
    lst = fibs(10)
    print(lst)

def fibs_tigui(n):
    if n == 0:
        return 0
    elif n == 1:
        return 1
    else:
        return fibs_tigui(n-1) + fibs_tigui(n-2)
if __name__ == "__main__":
    f = fibs_tigui(10)
    print(f)

'''递归优化
'''

meno = {0:0, 1:1} #初始化
def fib_better(n):
    if not n in meno: #如果不在初始化范围内
        meno[n] = fib_better(n-1) + fib_better(n-2)
    return meno[n]
if __name__ == "__main__":
    f_b = fib_better(10)
    print(f)