3Sum Unique Triplets | Dataford Interview Questions

FedEx SupplyChain may need to identify three shipment adjustments whose combined impact is zero. Given a list of integers nums, return every unique triplet [a, b, c] such that a + b + c = 0.

Each triplet must use three different positions from the input. Do not return duplicate triplets, even when nums contains repeated values. Return triplets in nondecreasing order, with the overall result in lexicographic order. If no valid triplet exists, return an empty list.

Formal Specification

Input: nums, a list of n integers.
Output: A list of lists containing every unique sorted triplet whose sum is zero.
The input list may be modified during processing.

Constraints

3 <= nums.length <= 3000
-10^5 <= nums[i] <= 10^5
Each triplet must use three different input positions
Return no duplicate triplets

Function Signature

def three_sum(nums):

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