Find Two Numbers That Sum | Dataford Interview Questions

Fiverr search services may need to identify two candidate gig scores whose combined value reaches a requested target. Given an integer array and a target integer, return the indices of two distinct elements whose values sum to the target.

Formal Specification

Implement two_sum(nums, target), where nums is a list of integers and target is an integer. Return a list containing the two zero-based indices [i, j], with i < j, such that nums[i] + nums[j] == target. Each input contains exactly one valid pair. Do not use the same array element twice.

Your solution should run in expected O(n) time. The returned indices may be in any order unless the implementation naturally returns them in ascending order.

Constraints

2 <= len(nums) <= 100,000
-10^9 <= nums[i] <= 10^9
-10^9 <= target <= 10^9
Exactly one valid pair exists
The same element cannot be used twice

Function Signature

def two_sum(nums, target):

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