## Problem Given an integer array `values` and an integer `target`, return the zero-based indices of two distinct elements whose sum equals `target`. There may be several valid pairs. Return the pair with the smallest second index; among pairs with that second index, return the one with the smallest first index. Return `[-1, -1]` if no pair exists. ### Function Contract Implement `twoSumEarliest(values, target)` and return a two-element integer array `[i, j]` with `i < j`. ### Constraints & Assumptions - `0 <= len(values) <= 200,000`. - Each value and `target` is between `-10^9` and `10^9`, inclusive. - Intermediate addition fits in a signed 64-bit integer. - The same array position may not be used twice, although equal values at different positions are allowed. ### Clarifying Questions to Ask - Is a solution guaranteed? No. - How are multiple solutions resolved? By the index rule in the prompt. - Should the input be modified? No. - Can negative values and duplicates appear? Yes. ```hint Scan in the order that defines the tie-break If second indices are considered from left to right, the first complement already seen determines the earliest pair for that position. ``` ### Examples - `values = [2, 7, 11, 15]`, `target = 9` returns `[0, 1]`. - `values = [3, 3]`, `target = 6` returns `[0, 1]`. - `values = [1, 4, 2, 3]`, `target = 5` returns `[0, 1]`, not `[2, 3]`. - `values = [5]`, `target = 10` returns `[-1, -1]`. ### Evaluation Focus - Applies the deterministic tie-break without sorting away original indices. - Handles duplicates, negatives, zero, and absence of a pair. - Runs in expected `O(n)` time with `O(n)` auxiliary space. ### Extensions to Discuss 1. What changes if the array is already sorted? 2. How would you count all index pairs instead of returning one? 3. What trade-off allows `O(1)` extra space if modifying the input is permitted?