Python: Find the three elements that sum to zero from a set of n real numbers

Last update on July 09 2025 10:45:27 (UTC/GMT +8 hours)

6. Find Three Elements that Sum to Zero

Write a Python class to find the three elements that sum to zero from a set (array) of n real numbers.

Sample Solution:

Python Code:

class py_solution:
 def threeSum(self, nums):
        nums, result, i = sorted(nums), [], 0
        while i < len(nums) - 2:
            j, k = i + 1, len(nums) - 1
            while j < k:
                if nums[i] + nums[j] + nums[k] < 0:
                    j += 1
                elif nums[i] + nums[j] + nums[k] > 0:
                    k -= 1
                else:
                    result.append([nums[i], nums[j], nums[k]])
                    j, k = j + 1, k - 1
                    while j < k and nums[j] == nums[j - 1]:
                        j += 1
                    while j < k and nums[k] == nums[k + 1]:
                        k -= 1
            i += 1
            while i < len(nums) - 2 and nums[i] == nums[i - 1]:
                i += 1
        return result

print(py_solution().threeSum([-25, -10, -7, -3, 2, 4, 8, 10]))

Sample Output:

[[-10, 2, 8], [-7, -3, 10]] 

Pictorial Presentation:

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python class that uses a brute-force approach with three nested loops to find all triplets in an array that sum to zero.
• Write a Python class that sorts the input array and then uses a two-pointer technique for each element to find zero-sum triplets.
• Write a Python class that implements a function using recursion to generate all combinations of three numbers and filter those that sum to zero.
• Write a Python class that leverages sets to avoid duplicate triplets when finding all three-element combinations that sum to zero.

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