Python 练习实例24

Python 100例

题目:有一分数序列:2/1,3/2,5/3,8/5,13/8,21/13...求出这个数列的前20项之和。

程序分析:请抓住分子与分母的变化规律。

程序源代码:

方法一:

实例

#!/usr/bin/python # -*- coding: UTF-8 -*- a = 2.0 b = 1.0 s = 0 for n in range(1,21): s += a / b t = a a = a + b b = t print s

方法二:

实例

#!/usr/bin/python # -*- coding: UTF-8 -*- a = 2.0 b = 1.0 s = 0.0 for n in range(1,21): s += a / b b,a = a , a + b print s s = 0.0 for n in range(1,21): s += a / b b,a = a , a + b print s

方法三:

实例

#!/usr/bin/python # -*- coding: UTF-8 -*- a = 2.0 b = 1.0 l = [] l.append(a / b) for n in range(1,20): b,a = a,a + b l.append(a / b) print reduce(lambda x,y: x + y,l)

以上实例输出结果为:

32.6602607986

Python 100例