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Python Data Structures and Algorithms - Recursion: Calculate the harmonic sum

Python Recursion: Exercise-8 with Solution

Write a Python program to calculate the harmonic sum of n-1.
Note: The harmonic sum is the sum of reciprocals of the positive integers.

Example:
harmonic series

Sample Solution:-

Python Code:

def harmonic_sum(n):
  if n < 2:
    return 1
  else:
    return 1 / n + (harmonic_sum(n - 1))
    
print(harmonic_sum(7))
print(harmonic_sum(4))

Sample Output:

2.5928571428571425                                                                                            
2.083333333333333

Flowchart:

Flowchart: Recursion: Calculate the harmonic sum.

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Previous: Write a Python program to calculate the sum of the positive integers of n+(n-2)+(n-4)... (until n-x =< 0).
Next: Write a Python program to calculate the geometric sum of n-1.

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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