Python Exercises: Sum of all list elements except current element

Last update on April 19 2025 13:00:41 (UTC/GMT +8 hours)

Sum Excluding Index

Write a Python program to add all elements of a list of integers except the number at index. Return the updated string.

Example: ([1, 2, 3]) -> [1+2+3-1, 1+2+3-2, 1+2+3-3]
-> [5, 4, 3].

Sample Data:
([0, 9, 2, 4, 5, 6] -> [26, 17, 24, 22, 21, 20]
([-4, 0, 6, 1, 0, 2]) -> [9, 5, -1, 4, 5, 3]
([1, 2, 3]) -> [5, 4, 3]
([-4, 0, 5, 1, 0, 1]) -> [7, 3, -2, 2, 3, 2]

Sample Solution:

Python Code:

# Define a function named 'test' that takes a list 'nums' as input.
def test(nums):
    # Use a list comprehension to calculate the sum of all elements in the 'nums' list,
    # and then subtract each element 'x' from the total sum. This gives the sum of all elements except the current one.
    return [sum(nums) - x for x in nums]

# Define the original list 'nums'.
nums = [0, 9, 2, 4, 5, 6]
print("Original list:")
print(nums)
# Call the 'test' function to calculate the sum of elements except the current element for each element in the list.
print("Sum of said list elements except the current element:\n", test(nums))

# Define another list 'nums'.
nums = [-4, 0, 6, 1, 0, 2]
print("\nOriginal list:")
print(nums)
# Call the 'test' function for the second list of numbers.
print("Sum of said list elements except the current element:\n", test(nums))

# Define another list 'nums'.
nums = [1, 2, 3]
print("\nOriginal list:")
print(nums)
# Call the 'test' function for the third list of numbers.
print("Sum of said list elements except the current element:\n", test(nums))

# Define another list 'nums'.
nums = [-4, 0, 5, 1, 0, 1]
print("\nOriginal list:")
print(nums)
# Call the 'test' function for the fourth list of numbers.
print("Sum of said list elements except the current element:\n", test(nums))

Sample Output:

Original list:
[0, 9, 2, 4, 5, 6]
Sum of said list elements except current element:
 [26, 17, 24, 22, 21, 20]

Original list:
[-4, 0, 6, 1, 0, 2]
Sum of said list elements except current element:
 [9, 5, -1, 4, 5, 3]

Original list:
[1, 2, 3]
Sum of said list elements except current element:
 [5, 4, 3]

Original list:
[-4, 0, 5, 1, 0, 1]
Sum of said list elements except current element:
 [7, 3, -2, 2, 3, 2]

Flowchart:

For more Practice: Solve these Related Problems:

Write a Python program to generate a new list where each element is the sum of all other elements in the original list excluding the current index.
Write a Python program to determine which index exclusion yields the maximum sum from a list of integers.
Write a Python program to compute a list of sums where each sum is the total of the list minus the element at that index, then compare these sums to a target value.
Write a Python program to return both the modified list and the index that results in the highest exclusion sum.

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