Two Sum Coding Task | Dataford Interview Questions

A CGI Nederland service workflow receives an unsorted list of integer identifiers and a target value. Implement a function that returns the indices of two distinct elements whose values add up to the target.

Formal Specification

Given an integer array nums and an integer target, return a list containing the two indices i and j such that nums[i] + nums[j] == target. Return the indices in ascending order of discovery. Each array element may be used at most once. Every valid input contains exactly one solution.

The function must return a Python list of two integers. Design an efficient solution suitable for large arrays.

Constraints

2 <= len(nums) <= 100,000
-10^9 <= nums[i] <= 10^9
-10^9 <= target <= 10^9
Exactly one pair satisfies the target sum
The same element cannot be selected twice

Function Signature

def two_sum(nums, target):

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