Python: Sum of all items of a given array of integers where each integer is multiplied by its index

Last update on May 24 2025 10:48:46 (UTC/GMT +8 hours)

Sum of Items Weighted by Index

Write a Python program to compute the sum of all items in a given array of integers where each integer is multiplied by its index. Return 0 if there is no number.

Sample Solution:

Python Code:

# Define a function named sum_index_multiplier that takes a list of numbers (nums) as an argument.
def sum_index_multiplier(nums):
    # Use a generator expression within the sum function to calculate the sum of each element multiplied by its index.
    # The expression j*i for i, j in enumerate(nums) iterates over the elements and their indices.
    return sum(j * i for i, j in enumerate(nums))

# Test the function with different lists of numbers and print the results.

# Test case 1
print(sum_index_multiplier([1,2,3,4]))

# Test case 2
print(sum_index_multiplier([-1,-2,-3,-4]))

# Test case 3
print(sum_index_multiplier([]))

Sample Output:

20
-20
0

Explanation:

Here is a breakdown of the above Python code:

• Function definition:
• The code defines a function named "sum_index_multiplier()" that takes a list of numbers (nums) as an argument.
• Generator Expression and Enumerate:

• The function uses a generator expression within the "sum()" function to calculate the sum of each element multiplied by its index. The expression j * i for i, j in enumerate(nums) iterates over the elements and their indices.

• The function returns the result of the sum operation.

Visual Presentation:

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to compute the weighted sum of a list of integers, where each element is multiplied by its index.
• Write a Python program to calculate the sum of products of each element in an array with its corresponding index using list comprehension.
• Write a Python program to determine the weighted sum of items by iterating with enumerate over the list.
• Write a Python program to compute the sum of list items multiplied by their indices and return 0 if the list is empty.

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