Two Sum Problem: Find Indices of Numbers Adding to Target

apple Given an unsorted array of integers, find two numbers such that they add up to a specific target number. The solution must have a time complexity less than O(n^2). Input An unsorted array of integers, e.g., [2, 7, 11, 15] An integer target value, e.g., 9 Output Return the indices of the two numbers in the form of an array, e.g., [0, 1] Note Assume each input would have exactly one solution, and you may not use the same element twice. Example Input: nums = [2, 7, 11, 15], target = 9 Output: [0, 1] Example Input 4 2 7 11 15 9