Python: Add two given lists of different lengths, start from right

Last update on April 19 2025 12:58:33 (UTC/GMT +8 hours)

Add Lists from Right

Write a Python program to add two given lists of different lengths, starting on the right.

Sample Solution:

Python Code:

def elementswise_right_join(l1, l2):
    f_len = len(l1)-(len(l2) - 1)
    for i in range(len(l1), 0, -1):
        if i-f_len < 0:
            break
        else:
            l1[i-1] = l1[i-1] + l2[i-f_len]
    return l1

nums1 = [2, 4, 7, 0, 5, 8]
nums2 = [3, 3, -1, 7]
print("\nOriginal lists:")
print(nums1)
print(nums2)
print("\nAdd said two lists from left:")
print(elementswise_right_join(nums1, nums2))

nums3 = [1, 2, 3, 4, 5, 6]
nums4 = [2, 4, -3]
print("\nOriginal lists:")
print(nums3)
print(nums4)
print("\nAdd said two lists from left:")
print(elementswise_right_join(nums3, nums4))

Sample Output:

Original lists:
[2, 4, 7, 0, 5, 8]
[3, 3, -1, 7]

Add said two lists from left:
[2, 4, 10, 3, 4, 15]

Original lists:
[1, 2, 3, 4, 5, 6]
[2, 4, -3]

Add said two lists from left:
[1, 2, 3, 6, 9, 3]

Flowchart:

For more Practice: Solve these Related Problems:

Write a Python program to add two lists of different lengths from the right, treating missing elements as zeros.
Write a Python program to add two lists from right and then reverse the digits of each resulting sum.
Write a Python program to add two lists from right and compute a running cumulative sum of the resulting values.
Write a Python program to add two lists from right but skip the addition when a negative element is encountered in the second list.

Go to:

Previous: Write a Python program to add two given lists of different lengths, start from left.
Next: Write a Python program to interleave multiple given lists of different lengths.

Python Code Editor: