# Two Sum - Part 2 - Interview Question

#dev

#interview-questions

Prerequisite:Basic HashMap, Array, Loop, and Big O knowledge.

This is Part 2 of a series.

##### ( Problem Recap )

Given an integer array and target, return the indices of the two numbers that add up to the target number.

Requirements:You may not use the same element twice.

##### ( Improving our answer )

Our Brute Force, nested loop answer, had a time complexity of `O(n^2)`

.

We can improve our time complexity if we get rid of the nested loop.