Python: Find the first two elements of a given list whose sum is equal to a given value

Last update on March 29 2025 13:02:43 (UTC/GMT +8 hours)

25. First Two Sum Elements

Write a Python program to find the first two elements of a given list whose sum is equal to a given value. Use the itertools module to solve the problem.

Sample Solution:

Python Code:

import itertools as it
def sum_pairs_list(nums, n):
    for num2, num1 in list(it.combinations(nums[::-1], 2))[::-1]:
        if num2 + num1 == n:
            return [num1, num2]

nums = [1,2,3,4,5,6,7]     
n = 10
print("Original list:",nums,": Given value:",n)   
print("Sum of pair equal to ",n,"=",sum_pairs_list(nums,n))

nums = [1,2,-3,-4,-5,6,-7]     
n = -6
print("Original list:",nums,": Given value:",n)   
print("Sum of pair equal to ",n,"=",sum_pairs_list(nums,n))

Sample Output:

Original list: [1, 2, 3, 4, 5, 6, 7] : Given value: 10
Sum of pair equal to  10 = [4, 6]
Original list: [1, 2, -3, -4, -5, 6, -7] : Given value: -6
Sum of pair equal to  -6 = [1, -7]

For more Practice: Solve these Related Problems:

• Write a Python program to find the first pair of consecutive elements in a list that sum to a given value using itertools.combinations.
• Write a Python program to iterate over a list and return the first two numbers whose sum equals a target, using a sliding window approach.
• Write a Python program to generate pairs from a list and then filter to find the first pair that matches the given sum.
• Write a Python program to use itertools to produce adjacent pairs from a list and then return the first pair with a sum equal to a specified value.

Python Code Editor:

Have another way to solve this solution? Contribute your code (and comments) through Disqus.

Previous: Write a Python program to find the maximum length of a substring in a given string where all the characters of the substring are same. Use itertools module to solve the problem.