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

Last update on May 30 2025 11:48:59 (UTC/GMT +8 hours)

Find Missing Number for Zero Total

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

Visual Presentation:

Sample Solution:

Python Code:

# Define a function named 'test' that takes a list of numbers as input
def test(nums):
    # Create a set 'dset' from the input list to remove duplicates
    dset = set(nums)
    # Initialize 'result' with the sum of the original list 'nums'
    result = sum(nums)
    # Calculate the absolute difference between the minimum value in 'nums' and the sum of the symmetric difference between 'dset' and 'nums'
    dmin = abs(min(nums) - sum(dset ^ set(nums)))
    
    # Iterate over the symmetric difference between 'dset' and 'nums'
    for d in dset ^ set(nums):
        # Create a copy of 'nums' and append the current value 'd'
        dcopy = list(nums)
        dcopy.append(d)
        # Calculate the sum of the modified list
        ds = sum(dcopy)
        
        # Check if the absolute value of the negation of the sum is less than 'dmin'
        if 0 - ds < dmin:
            result = ds
            dmin = abs(ds)
        # Check if the absolute value of the negation of the sum is equal to 'dmin'
        elif 0 - ds == dmin:
            # Update 'result' with the minimum value between the current 'result' and the calculated sum 'ds'
            result = min(result, ds)
    
    # Multiply the final result by -1 and return it
    return result * (-1)

# Set a list of numbers
nums = [1, 2, 3, 4, 5]
# Print a message indicating the original list of numbers
print("Original list of numbers:")
# Print the original list of numbers
print(nums)
# Print a message indicating the number that, when appended to the list, makes the total 0
print("Number which when appended to the list makes the total 0:")
# Print the result of the 'test' function applied to the numbers
print(test(nums)) 

# Set another list of numbers
nums = [-1, -2, -3, -4, 5]
# Print a message indicating the original list of numbers
print("\nOriginal list of numbers:")
# Print the original list of numbers
print(nums)
# Print a message indicating the number that, when appended to the list, makes the total 0
print("Number which when appended to the list makes the total 0:")
# Print the result of the 'test' function applied to the numbers
print(test(nums))  

# Set yet another list of numbers
nums = [10, 42, 17, 9, 1315182, 184, 102, 29, 15, 39, 755]
# Print a message indicating the original list of numbers
print("\nOriginal list of numbers:")
# Print the original list of numbers
print(nums)
# Print a message indicating the number that, when appended to the list, makes the total 0
print("Number which when appended to the list makes the total 0:")
# Print the result of the 'test' function applied to the numbers
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

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to compute the missing number which, when added to a list of integers, makes the total sum zero.
• Write a Python program to determine the additive inverse of the sum of a list and return it as the missing number.
• Write a Python program to use the sum() function to calculate the required number to bring a list’s sum to zero.
• Write a Python program to implement a function that returns the negation of the total sum of a list.

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Python Code Editor :

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