Basic Two Sum Problem | Dataford Interview Questions

An Itlize Global analytics dashboard receives a list of integer metric values and a target total. Find the two values whose sum equals the target and return their zero-based indices.

You may not use the same array element twice. Each valid input contains exactly one solution. Return the indices in ascending order. If no pair exists, return an empty list.

Formal Specification

Implement two_sum(nums, target).

Input: nums, a list of integers, and target, an integer.
Output: A list containing the two distinct zero-based indices whose values sum to target, or [] if no pair exists.

Use a dictionary to remember values already visited, allowing each complement lookup to be performed efficiently.

Constraints

2 <= len(nums) <= 10^4
-10^9 <= nums[i] <= 10^9
-10^9 <= target <= 10^9
Each valid input has at most one solution

Function Signature

def two_sum(nums, target):

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