Python: Find the number which when appended to the list makes the total 0

Last update on May 28 2022 13:41:16 (UTC/GMT +8 hours)

Python Programming Puzzles: Exercise-61 with Solution

Write a Python program to find the number which when appended to the list makes the total 0.

Input:
[1, 2, 3, 4, 5]
Output:
-15

Input:
[-1, -2, -3, -4, 5]
Output:
5

Input:
[10, 42, 17, 9, 1315182, 184, 102, 29, 15, 39, 755]
Output:
-1316384

Pictorial Presentation:

Python: Find the number which when appended to the list makes the total 0.

Sample Solution:

Python Code:

#License: https://bit.ly/3oLErEI

def test(nums):
    dset = set(nums)
    result = sum(nums)
    dmin = abs(min(nums) - sum(dset^set(nums)))
    for d in dset^set(nums):
        dcopy = list(nums)
        dcopy.append(d)
        ds = sum(dcopy)
        if 0-ds < dmin:
            result = ds
            dmin = abs(ds)
        elif 0-ds == dmin:
            result = min(result, ds)
    return result*(-1)
 
nums = [1, 2, 3, 4, 5]
print("Original list of numbers:")
print(nums)
print("Number which when appended to the list makes the total 0:")
print(test(nums)) 
nums = [-1, -2, -3, -4, 5]
print("\nOriginal list of numbers:")
print(nums)
print("Number which when appended to the list makes the total 0:")
print(test(nums))  
nums = [10, 42, 17, 9, 1315182, 184, 102, 29, 15, 39, 755]
print("\nOriginal list of numbers:")
print(nums)
print("Number which when appended to the list makes the total 0:")
print(test(nums))

Sample Output:

Original list of numbers:
[1, 2, 3, 4, 5]
Number which when appended to the list makes the total 0:
-15

Original list of numbers:
[-1, -2, -3, -4, 5]
Number which when appended to the list makes the total 0:
5

Original list of numbers:
[10, 42, 17, 9, 1315182, 184, 102, 29, 15, 39, 755]
Number which when appended to the list makes the total 0:
-1316384

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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