Implement lexicographically smallest Two Sum
Company: Walmart Labs
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Technical Screen
You are given an unsorted integer array `nums` and an integer `target`.
Return the indices `[i, j]` (0-based) such that `i < j` and `nums[i] + nums[j] == target`.
If there are multiple valid pairs, return the pair with the **smallest `i`**. If there is still a tie (same `i`), return the one with the **smallest `j`**.
Assume at least one valid pair exists.
Follow-up (discussion only): Explain an efficient approach to find all triplets `(i, j, k)` with `i < j < k` such that `nums[i] + nums[j] + nums[k] == 0`, and you may ignore duplicate triplets (or assume all numbers are distinct).
Quick Answer: This question evaluates array manipulation, index-level reasoning, and algorithmic efficiency for locating pair sums under lexicographic tie-breaking, testing attention to ordering constraints and correct index selection.