You are given an array of integers nums and an integer target. Return the indices of two numbers in the array such that they add up to target. You may assume that each input would have exactly one solution, and you may not use the same element twice. Implement a function in Java to solve this problem using a hash map, and explain the time and space complexity of your solution.

You are given an array of integers nums and an integer target. Return the indices of two numbers in the array such that they add up to target. You may assume that each input would have exactly one solution, and you may not use the same element twice. Implement a function in Java to solve this problem using a hash map, and explain the time and space complexity of your solution.