Two Sum - Part 2 - Interview Question

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.

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