Find two numbers that sum to a target

Array sum lookup

Given an integer array nums and an integer target, find two distinct indices i and j such that:

• nums[i] + nums[j] == target
• i != j

Return the pair of indices (in any order). If no such pair exists, return an empty result.

Clarifications to confirm in interview

• Are there negative numbers? (Assume yes.)
• If multiple answers exist, can we return any one? (Assume yes.)
• What output format is expected (0-based indices, 1-based indices, or the values themselves)? Specify and be consistent.

Constraints (typical)

• 1 <= nums.length <= 1e5
• -1e9 <= nums[i], target <= 1e9