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Python: List of integers where the sum of the first i integers is i

Python Programming Puzzles: Exercise-7 with Solution

Write a Python program to check a given list of integers where the sum of the first i integers is i. 

Input:
[0, 1, 2, 3, 4, 5]
Output:
False

Input:
[1, 1, 1, 1, 1, 1]
Output:
True

Input:
[2, 2, 2, 2, 2]
Output:
False

Pictorial Presentation:

Python: List of integers where the sum of the first i integers is i.
Python: List of integers where the sum of the first i integers is i.

Sample Solution:

Python Code:

#License: https://bit.ly/3oLErEI
 
def test(nums):
    return all([sum(nums[:i]) == i for i in range(len(nums))])
nums = [0,1,2,3,4,5]
print("Original list:")
print(nums)
print("Check the said list, where the sum of the first i integers is i:")
print(test(nums))
nums = [1,1,1,1,1,1]
print("\nOriginal list:")
print(nums)
print("Check the said list, where the sum of the first i integers is i:")
print(test(nums))
nums = [2,2,2,2,2]
print("\nOriginal list:")
print(nums)
print("Check the said list, where the sum of the first i integers is i:")
print(test(nums))

Sample Output:

Original list:
[0, 1, 2, 3, 4, 5]
Check the said list, where the sum of the first i integers is i:
False

Original list:
[1, 1, 1, 1, 1, 1]
Check the said list, where the sum of the first i integers is i:
True

Original list:
[2, 2, 2, 2, 2]
Check the said list, where the sum of the first i integers is i:
False

Flowchart:

Flowchart: Python - List of integers where the sum of the first i integers is i.

Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:


Python Code Editor :

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Previous: Find a list of one hundred integers between 0 and 999 which all differ by ten from one another.
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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