Python实现分数序列求和

我就废话不多说了，直接上代码吧！

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

"""
@version: python3.x
@author:曹新健
@contact: 617349013@qq.com
@software: PyCharm
@file: 1223.py
@time: 2018/12/23 20:56
"""

'''
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。
'''
"""
#方法一
def g(n):
 if n <= 2:
   return n
 else:
   return g(n-1) + g(n-2)
sum = 0
for i in range(1,21):
 sum += g(i+1)/g(i)
print(sum)
"""

#方法二
numerator = 2
denominator = 1
sum = 0
while True:
 try:
   n = int(input("请输入一个整数："))
 except ValueError:
   print("输入错误，请输入整数")
 else:
   for i in range(n):
     sum += numerator / denominator
     numerator, denominator = numerator + denominator, numerator

print(sum)
   break

补充拓展：Python分数加法的实现

或多或少大家都会觉得用电脑计算器不能显示分数很麻烦，所以用Python做一个分数加法是极好的

a = input()
b = a.split(',')

def eu(a,b):
 if a < b:
   a, b = b, a
 r = 1
 while r != 0:
   r = a ％ b
   a = b
   b = r
 return a

num1 = b[0].split('/')
num2 = b[1].split('/')
sum1 = int(num1[0])*int(num2[1]) + int(num2[0])*int(num1[1])
sum2 = int(num1[1])*int(num2[1])
GCD = eu(sum1,sum2)

c = int(sum1/GCD)
d = int(sum2/GCD)

if c％d == 0:
 print(int(c/d))
else:
 print(str(c)+ '/'+str(d))

实际上用fractions模块可以瞬间解决问题

from fractions import Fraction
a,b = (input().split(','))
sum=Fraction(a)+Fraction(b)
print(sum)

来源：https://blog.csdn.net/caoxinjian423/article/details/85370372