Python: Find the sum of the even elements that are at odd indices

Last update on May 30 2025 11:50:12 (UTC/GMT +8 hours)

Sum of Even Elements at Odd Indices

Write a Python program to find the sum of the even elements that are at odd indices in a given list.

Input:
[1, 2, 3, 4, 5, 6, 7]
Output:
12

Input:
[1, 2, 8, 3, 9, 4]
Output:
6

Visual Presentation:

Sample Solution-1:

Python Code:

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

def test(nums):
    # Sum the even elements at odd indices using list slicing and a conditional expression
    return sum(i for i in nums[1::2] if i % 2 == 0) 

# Example 1
nums1 = [1, 2, 3, 4, 5, 6, 7]
print("Original list of numbers:")
print(nums1)
print("Sum of the even elements of the said list that are at odd indices:")
print(test(nums1))

# Example 2
nums2 = [1, 2, 8, 3, 9, 4]
print("\nOriginal list of numbers:")
print(nums2)
print("Sum of the even elements of the said list that are at odd indices:")
print(test(nums2))

Sample Output:

Original list of numbers:
[1, 2, 3, 4, 5, 6, 7]
Sum of the even elements of the said list that are at odd indices:
12

Original list of numbers:
[1, 2, 8, 3, 9, 4]
Sum of the even elements of the said list that are at odd indices:
6

Flowchart:

Sample Solution-2:

Python Code:

def test(nums):
    # Sum the even elements at odd indices using a list comprehension
    return sum([nums[i] for i in range(len(nums)) if i % 2 == 1 and nums[i] % 2 == 0])

# Example 1
nums1 = [1, 2, 3, 4, 5, 6, 7]
print("Original list of numbers:")
print(nums1)
print("Sum of the even elements of the said list that are at odd indices:")
print(test(nums1))

# Example 2
nums2 = [1, 2, 8, 3, 9, 4]
print("\nOriginal list of numbers:")
print(nums2)
print("Sum of the even elements of the said list that are at odd indices:")
print(test(nums2))

Sample Output:

Original list of numbers:
[1, 2, 3, 4, 5, 6, 7]
Sum of the even elements of the said list that are at odd indices:
12

Original list of numbers:
[1, 2, 8, 3, 9, 4]
Sum of the even elements of the said list that are at odd indices:
6

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to sum only the even numbers that occur at odd indices in a list using enumerate.
• Write a Python program to filter out elements at odd indices and add them if they are even.
• Write a Python program to use list comprehension to extract even elements from odd positions and compute their sum.
• Write a Python program to implement a function that iterates over a list and conditionally sums elements based on index parity and evenness.

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