---
title: "What is a Hash Map? Time Complexity and Two Sum Example"
url: https://daily.dev/posts/what-is-a-hash-map-time-complexity-and-two-sum-example-fdlzfurww
source_url: https://www.freecodecamp.org/news/what-is-a-hash-map/
type: article
source: "freeCodeCamp"
published: 2024-01-25T19:19:37.631Z
updated: 2026-03-15T04:52:38.876Z
tags: ["data-science", "general-programming", "time-complexity"]
reading_time: 7
upvotes: 19
comments: 0
language: en
---

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# What is a Hash Map? Time Complexity and Two Sum Example

**[freeCodeCamp](https://daily.dev/sources/freecodecamp)** · 7 min read · 19 upvotes · 0 comments

## Summary

Learn about constant and linear time complexity, the use of hash maps, and how to solve the Two Sum problem using a hash table.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://www.freecodecamp.org/news/what-is-a-hash-map/>

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---

Tags: [#data-science](https://daily.dev/tags/data-science), [#general-programming](https://daily.dev/tags/general-programming), [#time-complexity](https://daily.dev/tags/time-complexity)

[View this post on daily.dev](https://daily.dev/posts/what-is-a-hash-map-time-complexity-and-two-sum-example-fdlzfurww)