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<h2 align="center">Hello Algo</h2>

<p align="center">Data Structures and Algorithms Crash Course with Animated Illustrations and Off-the-Shelf Code</p>

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<div class="admonition example" style="max-width: 800px;margin: 0 auto;">
  <p class="admonition-title">The English edition is brewing...</p>
  <p>Feel free to engage in Chinese-to-English translation and pull request review! For guidelines, please see <a href="https://github.com/krahets/hello-algo/issues/914">#914</a>.</p>
</div>

---

<h3 align="center">Endorsements</h3>

<div style="display: flex;">
  <div class="admonition quote" style="flex: 1; margin-right: 0.4rem;">
    <p class="admonition-title">Quote</p>
    <p>"An easy-to-understand book on data structures and algorithms, which guides readers to learn by minds-on and hands-on. Strongly recommended for algorithm beginners!"</p>
    <p><strong>—— Junhui Deng, Professor of Computer Science, Tsinghua University</strong></p>
  </div>
  <div class="admonition quote" style="flex: 1; margin-left: 0.4rem;">
    <p class="admonition-title">Quote</p>
    <p>"If I had 'Hello Algo' when I was learning data structures and algorithms, it would have been 10 times easier!"</p>
    <p><strong>—— Mu Li, Senior Principal Scientist, Amazon</strong></p>
  </div>
</div>

---

<div style="display: flex; align-items: center; margin: 2rem auto;">
  <div style="flex: 1; margin: 0 2rem; display: flex; flex-direction: column; align-items: center;">
    <div style="display: flex; flex-direction: column; align-items: center;">
      <h3>Animated illustrations</h3>
      <svg xmlns="http://www.w3.org/2000/svg" height="28" width="28" viewBox="0 0 640 512"><!--!Font Awesome Free 6.5.1 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free Copyright 2023 Fonticons, Inc.--><path fill="var(--md-primary-bg-color)" d="M256 0H576c35.3 0 64 28.7 64 64V288c0 35.3-28.7 64-64 64H256c-35.3 0-64-28.7-64-64V64c0-35.3 28.7-64 64-64zM476 106.7C471.5 100 464 96 456 96s-15.5 4-20 10.7l-56 84L362.7 169c-4.6-5.7-11.5-9-18.7-9s-14.2 3.3-18.7 9l-64 80c-5.8 7.2-6.9 17.1-2.9 25.4s12.4 13.6 21.6 13.6h80 48H552c8.9 0 17-4.9 21.2-12.7s3.7-17.3-1.2-24.6l-96-144zM336 96a32 32 0 1 0 -64 0 32 32 0 1 0 64 0zM64 128h96V384v32c0 17.7 14.3 32 32 32H320c17.7 0 32-14.3 32-32V384H512v64c0 35.3-28.7 64-64 64H64c-35.3 0-64-28.7-64-64V192c0-35.3 28.7-64 64-64zm8 64c-8.8 0-16 7.2-16 16v16c0 8.8 7.2 16 16 16H88c8.8 0 16-7.2 16-16V208c0-8.8-7.2-16-16-16H72zm0 104c-8.8 0-16 7.2-16 16v16c0 8.8 7.2 16 16 16H88c8.8 0 16-7.2 16-16V312c0-8.8-7.2-16-16-16H72zm0 104c-8.8 0-16 7.2-16 16v16c0 8.8 7.2 16 16 16H88c8.8 0 16-7.2 16-16V416c0-8.8-7.2-16-16-16H72zm336 16v16c0 8.8 7.2 16 16 16h16c8.8 0 16-7.2 16-16V416c0-8.8-7.2-16-16-16H424c-8.8 0-16 7.2-16 16z"/></svg>
    </div>
    <p style="text-align: center;">Easy to understand</br>Smooth learning curve</p>
  </div>
  <img src="index.assets/animation.gif" class="cover-image" style="flex-shrink: 0; width: auto; max-width: 50%; border-radius: 0.5rem;">
</div>

<div class="admonition quote">
  <p align="center">"A picture is worth a thousand words."</p>
</div>

<div style="display: flex; align-items: center; margin: 2rem auto;">
  <img src="index.assets/running_code.gif" class="cover-image" style="flex-shrink: 0; width: auto; max-width: 50%; border-radius: 0.5rem;">
  <div style="flex: 1; margin: 0 2rem; display: flex; flex-direction: column; align-items: center;">
    <div style="display: flex; flex-direction: column; align-items: center;">
      <h3>Off-the-Shelf Code</h3>
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    </div>
    <p style="text-align: center;">Multi programming languages</br>Run with one click</p>
  </div>
</div>

<div class="admonition quote">
  <p align="center">"Talk is cheap. Show me the code."</p>
</div>

<div style="display: flex; align-items: center; margin: 2rem auto;">
  <div style="flex: 1; margin: 0 2rem; display: flex; flex-direction: column; align-items: center;">
    <div style="display: flex; flex-direction: column; align-items: center;">
      <h3>Learning Together</h3>
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    </div>
    <p style="text-align: center;">Discussion and questions welcome</br>Readers progress together</p>
  </div>
  <img src="index.assets/comment.gif" class="cover-image" style="flex-shrink: 0; width: auto; max-width: 50%; border-radius: 0.5rem;">
</div>

<div class="admonition quote">
  <p align="center">"Chase the wind and moon, never stopping"</p>
  <p align="center">"Beyond the plains, there are spring mountains"</p>
</div>

---

<h3 align="center"> Preface </h3>

Two years ago, I shared the "Sword Offer" series of problem solutions on LeetCode, which received much love and support from many students. During my interactions with readers, the most common question I encountered was "How to get started with algorithms." Gradually, I developed a deep interest in this question.

Blindly solving problems seems to be the most popular method, being simple, direct, and effective. However, problem-solving is like playing a "Minesweeper" game, where students with strong self-learning abilities can successfully clear the mines one by one, but those with insufficient foundations may end up bruised from explosions, retreating step by step in frustration. Thoroughly reading textbooks is also common, but for students aiming for job applications, the energy consumed by graduation, resume submissions, and preparing for written tests and interviews makes tackling thick books a daunting challenge.

If you are facing similar troubles, then you are lucky to have found this book. This book is my answer to this question, not necessarily the best solution, but at least an active attempt. Although this book won't directly land you an Offer, it will guide you through the "knowledge map" of data structures and algorithms, help you understand the shape, size, and distribution of different "mines," and equip you with various "demining methods." With these skills, I believe you can more comfortably solve problems and read literature, gradually building a complete knowledge system.

I deeply agree with Professor Feynman's saying: "Knowledge isn't free. You have to pay attention." In this sense, this book is not entirely "free." To not disappoint the precious "attention" you pay to this book, I will do my utmost, investing the greatest "attention" to complete the creation of this book.

<h3 align="left"> Author </h3>

Yudong Jin([Krahets](https://leetcode.cn/u/jyd/)), Senior Algorithm Engineer in a top tech company, Master's degree from Shanghai Jiao Tong University. The highest-read blogger across the entire LeetCode, his published ["Illustration of Algorithm Data Structures"](https://leetcode.cn/leetbook/detail/illustration-of-algorithm/) has been subscribed to by over 300k.

---

<h3 align="center"> Contribution </h3>

This book is continuously improved with the joint efforts of many contributors from the open-source community. Thanks to each writer who invested their time and energy, listed in the order generated by GitHub:

<p align="center">
    <a href="https://github.com/krahets/hello-algo/graphs/contributors">
        <img width="550" src="https://contrib.rocks/image?repo=krahets/hello-algo">
    </a>
</p>

The code review work for this book was completed by codingonion, Gonglja, gvenusleo, hpstory, justin‐tse, krahets, night-cruise, nuomi1, and Reanon (listed in alphabetical order). Thanks to them for their time and effort, ensuring the standardization and uniformity of the code in various languages.

<div class="center-table">
    <table style="border: none;">
        <tbody>
          <td align="center" style="border: none;"><a href="https://github.com/codingonion"><img style="border-radius: 50%;" src="https://avatars.githubusercontent.com/u/99076655?v=4" width="50px;" alt="codingonion"/></br><sub><b>codingonion</b></sub></a></br><sub>Rust, Zig</sub></td>
          <td align="center" style="border: none;"><a href="https://github.com/Gonglja"><img style="border-radius: 50%;" src="https://avatars.githubusercontent.com/u/39959756?v=4" width="50px;" alt="Gonglja"/></br><sub><b>Gonglja</b></sub></a></br><sub>C, C++</sub></td>
          <td align="center" style="border: none;"><a href="https://github.com/gvenusleo"><img style="border-radius: 50%;" src="https://avatars.githubusercontent.com/u/79075347?v=4" width="50px;" alt="gvenusleo"/></br><sub><b>gvenusleo</b></sub></a></br><sub>Dart</sub></td>
          <td align="center" style="border: none;"><a href="https://github.com/hpstory"><img style="border-radius: 50%;" src="https://avatars.githubusercontent.com/u/33348162?v=4" width="50px;" alt="hpstory"/></br><sub><b>hpstory</b></sub></a></br><sub>C#</sub></td>
          <td align="center" style="border: none;"><a href="https://github.com/justin-tse"><img style="border-radius: 50%;" src="https://avatars.githubusercontent.com/u/24556310?v=4" width="50px;" alt="justin-tse"/></br><sub><b>justin-tse</b></sub></a></br><sub>JS, TS</sub></td>
          <td align="center" style="border: none;"><a href="https://github.com/krahets"><img style="border-radius: 50%;" src="https://avatars.githubusercontent.com/u/26993056?v=4" width="50px;" alt="krahets"/></br><sub><b>krahets</b></sub></a></br><sub>Java, Python</sub></td>
          <td align="center" style="border: none;"><a href="https://github.com/night-cruise"><img style="border-radius: 50%;" src="https://avatars.githubusercontent.com/u/77157236?v=4" width="50px;" alt="night-cruise"/></br><sub><b>night-cruise</b></sub></a></br><sub>Rust</sub></td>
          <td align="center" style="border: none;"><a href="https://github.com/nuomi1"><img style="border-radius: 50%;" src="https://avatars.githubusercontent.com/u/3739017?v=4" width="50px;" alt="nuomi1"/></br><sub><b>nuomi1</b></sub></a></br><sub>Swift</sub></td>
          <td align="center" style="border: none;"><a href="https://github.com/Reanon"><img style="border-radius: 50%;" src="https://avatars.githubusercontent.com/u/22005836?v=4" width="50px;" alt="Reanon"/></br><sub><b>Reanon</b></sub></a></br><sub>Go, C</sub></td>
        </tbody>
    </table>
</div>
