Python Challenges: Compute the sum of the even-valued terms in the Fibonacci sequence

Last update on May 28 2022 13:42:25 (UTC/GMT +8 hours)

Python Challenges - 1: Exercise-34 with Solution

Write a Python program to compute the sum of the even-valued terms in the Fibonacci sequence whose values do not exceed one million.

Note: Fibonacci series is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be: 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...

Sample Solution:-

Python Code:

cache = {}
def fiba(n):
     cache[n] = cache.get(n, 0) or (n <= 1 and 1 or fiba(n-1) + fiba(n-2))
     return cache[n]
n = 0
x = 0
while fiba(x) <= 1000000:
       if not fiba(x) % 2: n = n + fiba(x)
       x=x+1
print(n)

Sample Output:

Flowchart:

Python Code Editor:

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Previous: Write a Python program to compute the sum of all the multiples of 3 or 5 below 500.
Next: Write a Python program to find the largest prime factor of a given number.

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Python: Tips of the Day

Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os 
dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os
cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

The os and os.path modules.
The __file__ constant
os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
os.path.dirname(path) (returns "the directory name of pathname path")
os.getcwd() (returns "a string representing the current working directory")
os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m