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这本是《最优化导论》第四版课后习题配套答案。

《世界著名计算机教材精选·人工智能:一种现代的方法》是最权威、最经典的人工智能教材，已被全世界100多个国家的1200多所大学用作教材。《世界著名计算机教材精选·人工智能:一种现代的方法》的最新版全面而系统地介绍了人工智能的理论和实践，阐述了人工智能领域的核心内容，并深入介绍了各个主要的研究方向。全书分为七大部分：第Ⅰ部分“人工智能”，第Ⅱ部分“问题求解”，第Ⅲ部分“知识、推理与规划”，第Ⅳ部分“不确定知识与推理”，第Ⅴ部分“学习”，第Ⅵ部分“通信、感知与行动”，第Ⅶ部分“结论”。《世界著名计算机教材精选·人工智能:一种现代的方法》既详细介绍了人工智能的基本概念、思想和算法，还描述了其各个研究方向最前沿的进展，同时收集整理了详实的历史文献与事件。《世界著名计算机教材精选·人工智能:一种现代的方法》适合于不同层次和领域的研究人员及学生，是高等院校本科生和研究生人工智能课的首选教材，也是相关领域的科研与工程技术人员的重要参考书。

本书是被誉为UNIX编程“圣经”的Advanced Programming in the UNIX Environment一书的第3版。在本书第2版出版后的8年中，UNIX行业发生了巨大的变化，特别是影响UNIX编程接口的有关标准变化很大。本书在保持前一版风格的基础上，根据最新的标准对内容进行了修订和增补，反映了最新的技术发展。书中除了介绍UNIX文件和目录、标准I/O库、系统数据文件和信息、进程环境、进程控制、进程关系、信号、线程、线程控制、守护进程、各种I/O、进程间通信、网络IPC、伪终端等方面的内容，还在此基础上介绍了众多应用实例，包括如何创建数据库函数库以及如何与网络打印机通信等。此外，还在附录中给出了函数原型和部分习题的答案。 本书内容权威，概念清晰，阐述精辟，对于所有层次UNIX/Linux程序员都是一本不可或缺的参考书。

《神经网络与机器学习》的可读性非常强，作者举重若轻地对神经网络的基本模型和主要学习理论进行了深入探讨和分析，通过大量的试验报告、例题和习题来帮助读者更好地学习神经网络。神经网络是计算智能和机器学习的重要分支，在诸多领域都取得了很大的成功。在众多神经网络著作中，影响最为广泛的是SimonHaykin的《神经网络原理》(第4版更名为《神经网络与机器学习》）。在《神经网络与机器学习》中，作者结合近年来神经网络和机器学习的最新进展，从理论和实际应用出发，全面。系统地介绍了神经网络的基本模型、方法和技术，并将神经网络和机器学习有机地结合在一起。《神经网络与机器学习》不但注重对数学分析方法和理论的探讨，而且也非常关注神经网络在模式识别、信号处理以及控制系统等实际工程问题中的应用。 本版在前一版的基础上进行了广泛修订，提供了神经网络和机器学习这两个越来越重要的学科的最新分析。

作者Lippman参与设计了全世界首套C++编译程序cfront，这本《深度探索C++对象模型》就是一位伟大的C++编译程序设计者向你阐述他如何处理各种explicit（明确出现于C++程序代码中）和implicit（隐藏于程序代码背后）的C++语意。 《深度探索C++对象模型》专注于C++面向对象程序设计的底层机制，包括结构式语意、临时性对象的生成、封装、继承，以及虚拟——虚拟函数和虚拟继承。这本《深度探索C++对象模型》让你知道：一旦你能够了解底层实现模型，你的程序代码将获得多么大的效率。Lippman澄清了那些关于C++额外负荷与复杂度的各种错误信息和迷思，但也指出其中某些成本和利益交换确实存在。他阐述了各式各样的实现模型，指出它们的进化之道及其本质因素。书中涵盖了C++对象模型的语意暗示，并指出这个模型是如何影响你的程序的。 对于C++底层机制感兴趣的读者，这必然是一本让你大呼过瘾的绝妙好书。

《深入理解OpenCV:实用计算机视觉项目解析》内容简介：OpenCV是最常见的计算机视觉库之一，它提供了许多经过优化的复杂算法。《深入理解OpenCV:实用计算机视觉项目解析》对已掌握基本OpenCV技术同时想提高计算机视觉的实践经验的开发者来讲是一本非常好的书。每章都有一个单独的项目，其背景也在这些章节中进行了介绍。因此，读者可以依次学习这些项目，也可以直接跳到感兴趣的项目进行学习。《深入理解OpenCV:实用计算机视觉项目解析》详细讲解9个实用的计算机视觉项目，通过《深入理解OpenCV:实用计算机视觉项目解析》的学习，读者可以创建各种可运行的项目原型，例如，实时的移动应用、增强现实、从视频中获得三维形状、跟踪人脸和眼睛、车牌识别等。

1 排版 2 注释 3 标识符命名 4 可读性 5 变量、结构 6 函数、过程 7 可测性 8 程序效率 9 质量保证 10 代码编辑、编译、审查 11 代码测试、维护 12 宏

《人工智能复杂问题求解的结构和策略(原书第6版)》是一本经典的人工智能教材，全面阐述了人工智能的基础理论，有效结合了求解智能问题的数据结构以及实现的算法，把人工智能的应用程序应用于实际环境中，并从社会和哲学、心理学以及神经生理学角度对人工智能进行了独特的讨论。新版中增加了对“基于随机方法的机器学习”的介绍，并提出了一些新的主题，如涌现计算、本体论、随机分割算法等。 《人工智能复杂问题求解的结构和策略(原书第6版)》适合作为高等院校计算机专业人工智能教材，也可供人工智能领域的研究者及相关工程技术人员参考。

《统计学习方法》是计算机及其应用领域的一门重要的学科。《统计学习方法》全面系统地介绍了统计学习的主要方法，特别是监督学习方法，包括感知机、k近邻法、朴素贝叶斯法、决策树、逻辑斯谛回归与熵模型、支持向量机、提升方法、EM算法、隐马尔可夫模型和条件随机场等。除第1章概论和最后一章总结外，每章介绍一种方法。叙述从具体问题或实例入手，由浅入深，阐明思路，给出必要的数学推导，便于读者掌握统计学习方法的实质，学会运用。为满足读者进一步学习的需要，书中还介绍了一些相关研究，给出了少量习题，列出了主要参考文献。

本书是一本关于最优化技术的入门教材，全书共分为四部分。第一部分是预备知识。第二部分主要介绍无约束的优化问题，并介绍线性方程的求解方法、神经网络方法和全局搜索方法。第三部分介绍线性优化问题，包括线性优化问题的模型、单纯形法、对偶理论以及一些非单纯形法，简单介绍了整数线性优化问题。第四部分介绍有约束非线性优化问题，包括纯等式约束下和不等式约束下的优化问题的最优性条件、凸优化问题、有约束非线性优化问题的求解算法和多目标优化问题。

本书详细介绍了密度估计（分参数、贝叶斯和非参数三章）、线性判别分析、非线性判别分析、决策树归纳、多分类器融合、性能估计、聚类法、复杂网络等内容。 Statistical pattern recognition relates to the use of statistical techniques for analysing data measurements in order to extract information and make justified decisions. It is a very active area of study and research, which has seen many advances in recent years. Applications such as data mining, web searching, multimedia data retrieval, face recognition, and cursive handwriting recognition, all require robust and efficient pattern recognition techniques.

《技术之瞳——阿里巴巴技术笔试心得》由阿里巴巴集团校园招聘笔试项目组所著，收集了阿里历年校招中的精华笔试题，涉 及多个领域。《技术之瞳——阿里巴巴技术笔试心得》中内容大量结合了阿里巴巴的实际工作场景，以例题、解析、习题的形式，引 导读者深入理解技术上的关键点、紧要处，夯实基础，启发思考。《技术之瞳——阿里巴巴技术笔试心得》内容不仅专业、有趣，更 是将理论知识与实践应用结合起来，以场景化的问答娓娓道来！

Introduction to Probability Models，随机过程的权威著作，有爱者自取之。

人脸识别方面的专业资料图书，研究以及相关系统开发参考。有爱者自取之。

vim被誉为编辑器之神，这本书是很好的学习资源。有爱者自取之。

我所读过OpenGL最好的一本书，强烈推荐。有识者自爱之。

OpenGL开发圣经，经典实用，有识者自爱之。

OpenGL相关开发不得不看的很经典一本书，有识者自爱之。

opencv很经典的一本书，有识者自爱之。

opencv很经典的一本书，有识者自爱之。

the_c_standard_library_2nd_edition.pdf 提高c++技术的一本必读书，此书对C++标准库的描述解释无出其右者，有识者爱之。

The.C++.Programming.Language.4th.Edition.pdf C++的权威指导书，覆盖C++11标准，有识者爱之。

Code Complete.pdf 代码大全，非常好的一本程序员的编程指导，行业规范。

Pattern Recognition 4th Edition.pdf，模式识别，计算机科学模式识别领域的殿堂级神书。

Head First Design Patterns .pdf中文译作深入浅出设计模式，非常好的一本书，有识者爱之。

二维装箱问题的非线性优化方法

阿里巴巴2016数据挖掘工程师笔试及答案

《Python标准库》中文版

基于视觉的目标检测与跟踪综述。

正则化稀疏模型

半监督学习方法.pdf

Python3简明教程，入门材料。

卷积神经网络研究综述，很详细。

深度学习大牛Bengio大作，深度学习绝好人们材料。

《Python数据分析基础教程：NumPy学习指南(第2版)》是NumPy的入门教程，主要介绍NumPy以及相关的Python科学计算库，如SciPy和Matplotlib。《Python数据分析基础教程：NumPy学习指南(第2版)》内容涵盖NumPy安装、数组对象、常用函数、矩阵运算、线性代数、金融函数、窗函数、质量控制、Matplotlib绘图、SciPy简介以及Pygame等内容，涉及面较广。另外，Ivan Idris针对每个知识点给出了简短而明晰的示例，并为大部分示例给出了实用场景(如股票数据分析)，在帮助初学者入门的同时，提高了本书可读性。 《Python数据分析基础教程：NumPy学习指南(第2版)》适合正在找寻高质量开源计算库的科学家、工程师、程序员和定量管理分析师阅读参考。

Python是一种脚本语言，在各个领域得到了日益广泛的应用。《Python 3程序开发指南（第2版 修订版）》全面深入地对Python语言进行了讲解。 《Python 3程序开发指南（第2版 修订版）》首先讲述了构成Python语言的8个关键要素，之后分章节对其进行了详尽的阐述，包括数据类型、控制结构与函数、模块、文件处理、调试、进程与线程、网络、数据库、正则表达式、GUI程序设计等各个方面，并介绍了其他一些相关主题。全书内容以实例讲解为主线，每章后面附有练习题，便于读者更好地理解和掌握所讲述的内容。 《Python 3程序开发指南（第2版 修订版）》适合于作为Python语言教科书使用，对Python程序设计人员也有一定的参考价值。

受限玻尔兹曼机RBM的C++11实现

# [LeetCode](https://leetcode.com/problemset/algorithms/)  [](./LICENSE.md)  Up to date (2016-12-18), there are `447` Algorithms / `13` Database / `4` Shell / `4` Draft questions on [LeetCode Online Judge](https://leetcode.com/). The number of questions is increasing recently. Here is the classification of all `468` questions. For more questions and solutions, you can see my [LintCode](https://github.com/kamyu104/LintCode) repository. I'll keep updating for full summary and better solutions. Stay tuned for updates. (Notes: "馃摉" means you need to subscribe to [LeetCode premium membership](https://leetcode.com/subscribe/) for the access to premium questions.) ## Algorithms * [Bit Manipulation](https://github.com/kamyu104/LeetCode#bit-manipulation) * [Array](https://github.com/kamyu104/LeetCode#array) * [String](https://github.com/kamyu104/LeetCode#string) * [Linked List](https://github.com/kamyu104/LeetCode#linked-list) * [Stack](https://github.com/kamyu104/LeetCode#stack) * [Queue](https://github.com/kamyu104/LeetCode#queue) * [Heap](https://github.com/kamyu104/LeetCode#heap) * [Tree](https://github.com/kamyu104/LeetCode#tree) * [Hash Table](https://github.com/kamyu104/LeetCode#hash-table) * [Data Structure](https://github.com/kamyu104/LeetCode#data-structure) * [Math](https://github.com/kamyu104/LeetCode#math) * [Two Pointers](https://github.com/kamyu104/LeetCode#two-pointers) * [Sort](https://github.com/kamyu104/LeetCode#sort) * [Recursion](https://github.com/kamyu104/LeetCode#recursion) * [Binary Search](https://github.com/kamyu104/LeetCode#binary-search) * [Binary Search Tree](https://github.com/kamyu104/LeetCode#binary-search-tree) * [Breadth-First Search](https://github.com/kamyu104/LeetCode#breadth-first-search) * [Depth-First Search](https://github.com/kamyu104/LeetCode#depth-first-search) * [Backtracking](https://github.com/kamyu104/LeetCode#backtracking) * [Dynamic Programming](https://github.com/kamyu104/LeetCode#dynamic-programming) * [Greedy](https://github.com/kamyu104/LeetCode#greedy) * [Design](https://github.com/kamyu104/LeetCode#design) ## Database * [SQL](https://github.com/kamyu104/LeetCode#sql) ## Shell * [Shell Script](https://github.com/kamyu104/LeetCode#shell-script) ## Bit Manipulation | # | Title | Solution | Time | Space | Difficulty | Tag | Note| |-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----| 136 | [Single Number](https://leetcode.com/problems/single-number/) | [C++](./C++/single-number.cpp) [Python](./Python/single-number.py) | _O(n)_ | _O(1)_ | Easy ||| 137 | [Single Number II](https://leetcode.com/problems/single-number-ii/) | [C++](./C++/single-number-ii.cpp) [Python](./Python/single-number-ii.py) | _O(n)_ | _O(1)_ | Medium ||| 190 | [Reverse Bits](https://leetcode.com/problems/reverse-bits/) | [C++](./C++/reverse-bits.cpp) [Python](./Python/reverse-bits.py) | _O(1)_ | _O(1)_ | Easy ||| 191 |[Number of 1 Bits](https://leetcode.com/problems/number-of-1-bits/) | [C++](./C++/number-of-1-bits.cpp) [Python](./Python/number-of-1-bits.py) | _O(1)_ | _O(1)_ | Easy ||| 201 | [Bitwise AND of Numbers Range](https://leetcode.com/problems/bitwise-and-of-numbers-range/) | [C++](./C++/bitwise-and-of-numbers-range.cpp) [Python](./Python/bitwise-and-of-numbers-range.py) | _O(1)_ | _O(1)_ | Medium || 231 | [Power of Two](https://leetcode.com/problems/power-of-two/) | [C++](./C++/power-of-two.cpp) [Python](./Python/power-of-two.py) | _O(1)_ | _O(1)_ | Easy | LintCode | 260 | [Single Number III](https://leetcode.com/problems/single-number-iii/) | [C++](./C++/single-number-iii.cpp) [Python](./Python/single-number-iii.py) | _O(n)_ | _O(1)_ | Medium || 268| [Missing Number](https://leetcode.com/problems/missing-number/) | [C++](./C++/missing-number.cpp) [Python](./Python/missing-number.py) | _O(n)_ | _O(1)_ | Medium | LintCode || 318| [Maximum Product of Word Lengths](https://leetcode.com/problems/maximum-product-of-word-lengths/) | [C++](./C++/maximum-product-of-word-lengths.cpp) [Python](./Python/maximum-product-of-word-lengths.py) | _O(n)_ ~ _O(n^2)_ | _O(n)_ | Medium || Bit Manipulation, Counting Sort, Pruning| 342 | [Power of Four](https://leetcode.com/problems/power-of-four/) | [C++](./C++/power-of-four.cpp) [Python](./Python/power-of-four.py) | _O(1)_ | _O(1)_ | Easy | | 371 | [Sum of Two Integers](https://leetcode.com/problems/sum-of-two-integers/) | [C++](./C++/sum-of-two-integers.cpp) [Python](./Python/sum-of-two-integers.py) | _O(1)_ | _O(1)_ | Easy | LintCode | 389 | [Find the Difference](https://leetcode.com/problems/find-the-difference/) | [C++](./C++/find-the-difference.cpp) [Python](./Python/find-the-difference.py) | _O(n)_ | _O(1)_ | Easy | | 393 | [UTF-8 Validation](https://leetcode.com/problems/utf-8-validation/) | [C++](./C++/utf-8-validation.cpp) [Python](./Python/utf-8-validation.py) | _O(n)_ | _O(1)_ | Medium | | 401 | [Binary Watch](https://leetcode.com/problems/binary-watch/) | [C++](./C++/binary-watch.cpp) [Python](./Python/binary-watch.py) | _O(1)_ | _O(1)_ | Easy | | 411 | [Minimum Unique Word Abbreviation](https://leetcode.com/problems/minimum-unique-word-abbreviation/) | [C++](./C++/minimum-unique-word-abbreviation.cpp) [Python](./Python/minimum-unique-word-abbreviation.py) | _O(2^n)_ | _O(n)_ | Hard | 馃摉 | 421 | [Maximum XOR of Two Numbers in an Array](https://leetcode.com/problems/maximum-xor-of-two-numbers-in-an-array/) | [C++](./C++/maximum-xor-of-two-numbers-in-an-array.cpp) [Python](./Python/maximum-xor-of-two-numbers-in-an-array.py) | _O(n)_ | _O(1)_ | Medium || 461 | [Hamming Distance](https://leetcode.com/problems/hamming-distance/) | [C++](./C++/hamming-distance.cpp) [Python](./Python/hamming-distance.py) | _O(1)_ | _O(1)_ | Easy || 462 | [Minimum Moves to Equal Array Elements II](https://leetcode.com/problems/minimum-moves-to-equal-array-elements-ii/) | [C++](./C++/minimum-moves-to-equal-array-elements-ii.cpp) [Python](./Python/minimum-moves-to-equal-array-elements-ii.py) | _O(n)_ on average | _O(1)_ | Medium || 477 | [Total Hamming Distance](https://leetcode.com/problems/total-hamming-distance/) | [C++](./C++/total-hamming-distance.cpp) [Python](./Python/total-hamming-distance.py) | _O(n)_ | _O(1)_ | Medium || ## Array | # | Title | Solution | Time | Space | Difficulty | Tag | Note| |-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----| 15 | [3 Sum](https://leetcode.com/problems/3sum/) | [C++](./C++/3sum.cpp) [Python](./Python/3sum.py) | _O(n^2)_ | _O(1)_ | Medium || Two Pointers 16 | [3 Sum Closest](https://leetcode.com/problems/3sum-closest/) | [C++](./C++/3sum-closest.cpp) [Python](./Python/3sum-closest.py) | _O(n^2)_ | _O(1)_ | Medium || Two Pointers 18| [4 Sum](https://leetcode.com/problems/4sum/) | [C++](./C++/4sum.cpp) [Python](./Python/4sum.py) | _O(n^3)_ | _O(1)_ | Medium || Two Pointers 26 | [Remove Duplicates from Sorted Array](https://leetcode.com/problems/remove-duplicates-from-sorted-array/)| [C++](./C++/remove-duplicates-from-sorted-array.cpp) [Python](./Python/remove-duplicates-from-sorted-array.py) | _O(n)_ | _O(1)_ | Easy || Two Pointers 27 | [Remove Element](https://leetcode.com/problems/remove-element/) | [C++](./C++/remove-element.cpp) [Python](./Python/remove-element.py) | _O(n)_ | _O(1)_ | Easy || 31 | [Next Permutation](https://leetcode.com/problems/next-permutation/)| [C++](./C++/next-permutation.cpp) [Python](./Python/next-permutation.py) | _O(n)_ | _O(1)_ | Medium || Tricky 41 | [First Missing Positive](https://leetcode.com/problems/first-missing-positive/)| [C++](./C++/first-missing-positive.cpp) [Python](./Python/first-missing-positive.py) | _O(n)_ | _O(1)_ | Hard || Tricky 48 | [Rotate Image](https://leetcode.com/problems/rotate-image/) | [C++](./C++/rotate-image.cpp) [Python](./Python/rotate-image.py) | _O(n^2)_ | _O(1)_ | Medium || 54 | [Spiral Matrix](https://leetcode.com/problems/spiral-matrix/) | [C++](./C++/spiral-matrix.cpp) [Python](./Python/spiral-matrix.py) | _O(m * n)_ | _O(1)_ | Medium || 59 | [Spiral Matrix II](https://leetcode.com/problems/spiral-matrix-ii/) | [C++](./C++/spiral-matrix-ii.cpp) [Python](./Python/spiral-matrix-ii.py) | _O(n^2)_ | _O(1)_ | Medium || 66 | [Plus One](https://leetcode.com/problems/plus-one/) | [C++](./C++/plus-one.cpp) [Python](./Python/plus-one.py) | _O(n)_ | _O(1)_ | Easy || 73 | [Set Matrix Zeroes](https://leetcode.com/problems/set-matrix-zeroes/) | [C++](./C++/set-matrix-zeroes.cpp) [Python](./Python/set-matrix-zeroes.py) | _O(m * n)_ | _O(1)_ | Medium || 80 | [Remove Duplicates from Sorted Array II](https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii/)| [C++](./C++/remove-duplicates-from-sorted-array-ii.cpp) [Python](./Python/remove-duplicates-from-sorted-array-ii.py) | _O(n)_ | _O(1)_ | Medium || Two Pointers 118 | [Pascal's Triangle](https://leetcode.com/problems/pascals-triangle/)| [C++](./C++/pascals-triangle.cpp) [Python](./Python/pascals-triangle.py) | _O(n^2)_ | _O(1)_ | Easy || 119 | [Pascal's Triangle II](https://leetcode.com/problems/pascals-triangle-ii/)| [C++](./C++/pascals-triangle-ii.cpp) [Python](./Python/pascals-triangle-ii.py) | _O(n^2)_ | _O(1)_ | Easy || 121 | [Best Time to Buy and Sell Stock](https://leetcode.com/problems/best-time-to-buy-and-sell-stock/)| [C++](./C++/best-time-to-buy-and-sell-stock.cpp) [Python](./Python/best-time-to-buy-and-sell-stock.py) | _O(n)_ | _O(1)_ | Easy || 128 | [Longest Consecutive Sequence](https://leetcode.com/problems/longest-consecutive-sequence/)| [C++](./C++/longest-consecutive-sequence.cpp) [Python](./Python/longest-consecutive-sequence.py) | _O(n)_ | _O(n)_ | Hard || Tricky 157 | [Read N Characters Given Read4](https://leetcode.com/problems/read-n-characters-given-read4/) | [C++](./C++/read-n-characters-given-read4.cpp) [Python](./Python/read-n-characters-given-read4.py) | _O(n)_ | _O(1)_ | Easy |馃摉| 158 | [Read N Characters Given Read4 II - Call multiple times](https://leetcode.com/problems/read-n-characters-given-read4-ii-call-multiple-times/) | [C++](./C++/read-n-characters-given-read4-ii-call-multiple-times.cpp) [Python](./Python/read-n-characters-given-read4-ii-call-multiple-times.py) | _O(n)_ | _O(1)_ | Hard |馃摉| 163 | [Missing Ranges](https://leetcode.com/problems/missing-ranges/)| [C++](./C++/missing-ranges.cpp) [Python](./Python/missing-ranges.py) | _O(n)_ | _O(1)_ | Medium | 馃摉 | 169 | [Majority Element](https://leetcode.com/problems/majority-element/) | [C++](./C++/majority-element.cpp) [Python](./Python/majority-element.py) | _O(n)_ | _O(1)_ | Easy | 189 | [Rotate Array](https://leetcode.com/problems/rotate-array/) | [C++](./C++/rotate-array.cpp) [Python](./Python/rotate-array.py) | _O(n)_ | _O(1)_ | Easy || 209 | [Minimum Size Subarray Sum](https://leetcode.com/problems/minimum-size-subarray-sum/) | [C++](./C++/minimum-size-subarray-sum.cpp) [Python](./Python/minimum-size-subarray-sum.py) | _O(n)_ | _O(1)_ | Medium | | Binary Search 215 | [Kth Largest Element in an Array](https://leetcode.com/problems/kth-largest-element-in-an-array/) | [C++](./C++/kth-largest-element-in-an-array.cpp) [Python](./Python/kth-largest-element-in-an-array.py)| _O(n)_ ~ _O(n^2)_ | _O(1)_ | Medium | EPI| 228 | [Summary Ranges](https://leetcode.com/problems/summary-ranges/) | [C++](./C++/summary-ranges.cpp) [Python](./Python/summary-ranges.py)| _O(n)_ | _O(1)_ | Medium | | 229 | [Majority Element II](https://leetcode.com/problems/majority-element-ii/) | [C++](./C++/majority-element-ii.cpp) [Python](./Python/majority-element-ii.py) | _O(n)_ | _O(1)_ | Medium | | 238 | [Product of Array Except Self](https://leetcode.com/problems/product-of-array-except-self/) | [C++](./C++/product-of-array-except-self.cpp) [Python](./Python/product-of-array-except-self.py) | _O(n)_ | _O(1)_ | Medium | LintCode | 240 | [Search a 2D Matrix II](https://leetcode.com/problems/search-a-2d-matrix-ii/) | [C++](./C++/search-a-2d-matrix-ii.cpp) [Python](./Python/search-a-2d-matrix-ii.py) | _O(m + n)_ | _O(1)_ | Medium | EPI, LintCode | 243| [Shortest Word Distance](https://leetcode.com/problems/shortest-word-distance/) | [C++](./C++/shortest-word-distance.cpp) [Python](./Python/shortest-word-distance.py) | _O(n)_ | _O(1)_ | Easy |馃摉|| 245| [Shortest Word Distance III](https://leetcode.com/problems/shortest-word-distance-iii/) | [C++](./C++/shortest-word-distance-iii.cpp) [Python](./Python/shortest-word-distance-iii.py) | _O(n)_ | _O(1)_ | Medium |馃摉|| 251| [Flatten 2D Vector](https://leetcode.com/problems/flatten-2d-vector/) | [C++](./C++/flatten-2d-vector.cpp) [Python](./Python/flatten-2d-vector.py) | _O(1)_ | _O(1)_ | Medium |馃摉|| 277| [Find the Celebrity](https://leetcode.com/problems/find-the-celebrity/) | [C++](./C++/find-the-celebrity.cpp) [Python](./Python/find-the-celebrity.py) | _O(n)_ | _O(1)_ | Medium |馃摉, EPI || 289| [Game of Life](https://leetcode.com/problems/game-of-life/) | [C++](./C++/game-of-life.cpp) [Python](./Python/game-of-life.py) | _O(m * n)_ | _O(1)_ | Medium ||| 293| [Flip Game](https://leetcode.com/problems/flip-game/) | [C++](./C++/flip-game.cpp) [Python](./Python/flip-game.py) | _O(n * (c+1))_ | _O(1)_ | Easy |馃摉|| 296| [Best Meeting Point](https://leetcode.com/problems/best-meeting-point/) | [C++](./C++/best-meeting-point.cpp) [Python](./Python/best-meeting-point.py) | _O(m * n)_ | _O(m + n)_ | Hard |馃摉|| 311| [Sparse Matrix Multiplication](https://leetcode.com/problems/sparse-matrix-multiplication/) | [C++](./C++/sparse-matrix-multiplication.cpp) [Python](./Python/sparse-matrix-multiplication.py) | _O(m * n * l)_ | _O(m * l)_ | Medium |馃摉|| 334| [Increasing Triplet Subsequence](https://leetcode.com/problems/increasing-triplet-subsequence/) | [C++](./C++/increasing-triplet-subsequence.cpp) [Python](./Python/increasing-triplet-subsequence.py) | _O(n)_ | _O(1)_ | Medium ||| 370| [Range Addition](https://leetcode.com/problems/range-addition/) | [C++](./C++/range-addition.cpp) [Python](./Python/range-addition.py) | _O(k + n)_ | _O(1)_ | Medium |馃摉|| 384| [Shuffle an Array](https://leetcode.com/problems/shuffle-an-array/) | [C++](./C++/shuffle-an-array.cpp) [Python](./Python/shuffle-an-array.py) | _O(n)_ | _O(n)_ | Medium | EPI || 396| [Rotate Function](https://leetcode.com/problems/rotate-function/) | [C++](./C++/rotate-function.cpp) [Python](./Python/rotate-function.py) | _O(n)_ | _O(1)_ | Easy ||| 412| [Fizz Buzz](https://leetcode.com/problems/fizz-buzz/) | [C++](./C++/fizz-buzz.cpp) [Python](./Python/fizz-buzz.py) | _O(n)_ | _O(1)_ | Easy ||| 414| [Third Maximum Number](https://leetcode.com/problems/third-maximum-number/) | [C++](./C++/third-maximum-number.cpp) [Python](./Python/third-maximum-number.py) | _O(n)_ | _O(1)_ | Easy ||| 419| [Battleships in a Board](https://leetcode.com/problems/battleships-in-a-board/) | [C++](./C++/battleships-in-a-board.cpp) [Python](./Python/battleships-in-a-board.py) | _O(m * n)_ | _O(1)_ | Medium ||| 422| [Valid Word Square](https://leetcode.com/problems/valid-word-square/) | [C++](./C++/valid-word-square.cpp) [Python](./Python/valid-word-square.py) | _O(m * n)_ | _O(1)_ | Easy |馃摉|| 442| [Find All Duplicates in an Array](https://leetcode.com/problems/find-all-duplicates-in-an-array/) | [C++](./C++/find-all-duplicates-in-an-array.cpp) [Python](./Python/find-all-duplicates-in-an-array.py) | _O(n)_ | _O(1)_ | Medium ||| 448| [Find All Numbers Disappeared in an Array](https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array/) | [C++](./C++/find-all-numbers-disappeared-in-an-array.cpp) [Python](./Python/find-all-numbers-disappeared-in-an-array.py) | _O(n)_ | _O(1)_ | Easy ||| ## String | # | Title | Solution | Time | Space | Difficulty | Tag | Note| |-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----| 5| [Longest Palindromic Substring](https://leetcode.com/problems/longest-palindromic-substring/) | [C++](./C++/longest-palindromic-substring.cpp) [Python](./Python/longest-palindromic-substring.py) | _O(n)_ | _O(n)_ | Medium || `Manacher's Algorithm` 6| [ZigZag Conversion](https://leetcode.com/problems/zigzag-conversion/) | [C++](./C++/zigzag-conversion.cpp) [Python](./Python/zigzag-conversion.py) | _O(n)_ | _O(1)_ | Easy || 8| [String to Integer (atoi)](https://leetcode.com/problems/string-to-integer-atoi/) | [C++](./C++/string-to-integer-atoi.cpp) [Python](./Python/string-to-integer-atoi.py) | _O(n)_ | _O(1)_ | Easy || 14| [Longest Common Prefix](https://leetcode.com/problems/longest-common-prefix/) | [C++](./C++/longest-common-prefix.cpp) [Python](./Python/longest-common-prefix.py) | _O(n * k)_ | _O(1)_ | Easy || 28| [Implement strStr()](https://leetcode.com/problems/implement-strstr/) | [C++](./C++/implement-strstr.cpp) [Python](./Python/implement-strstr.py) | _O(n + k)_ | _O(k)_ | Easy || `KMP Algorithm` 38| [Count and Say](https://leetcode.com/problems/count-and-say/) | [C++](./C++/count-and-say.cpp) [Python](./Python/count-and-say.py)| _O(n * 2^n)_ | _O(2^n)_ | Easy || 43| [Multiply Strings](https://leetcode.com/problems/multiply-strings/) | [C++](./C++/multiply-strings.cpp) [Python](./Python/multiply-strings.py) | _O(m * n)_ | _O(m + n)_ | Medium || 58| [Length of Last Word](https://leetcode.com/problems/length-of-last-word/) | [C++](./C++/length-of-last-word.cpp) [Python](./Python/length-of-last-word.py) | _O(n)_ | _O(1)_ | Easy || 67| [Add Binary](https://leetcode.com/problems/add-binary/) | [C++](./C++/add-binary.cpp) [Python](./Python/add-binary.py) | _O(n)_ | _O(1)_ | Easy || 68| [Text Justification](https://leetcode.com/problems/text-justification/) | [C++](./C++/text-justification.cpp) [Python](./Python/text-justification.py) | _O(n)_ | _O(1)_ | Hard || 125| [Valid Palindrome](https://leetcode.com/problems/valid-palindrome/) | [C++](./C++/valid-palindrome.cpp) [Python](./Python/valid-palindrome.py) | _O(n)_ | _O(1)_ | Easy || 151| [Reverse Words in a String](https://leetcode.com/problems/reverse-words-in-a-string/) | [C++](./C++/reverse-words-in-a-string.cpp) [Python](./Python/reverse-words-in-a-string.py) | _O(n)_ | _O(1)_ | Medium || 161| [One Edit Distance](https://leetcode.com/problems/one-edit-distance/) | [C++](./C++/one-edit-distance.cpp) [Python](./Python/one-edit-distance.py) | _O(m + n)_ | _O(1)_ | Medium |馃摉 | 165| [Compare Version Numbers](https://leetcode.com/problems/compare-version-numbers/) | [C++](./C++/compare-version-numbers.cpp) [Python](./Python/compare-version-numbers.py) | _O(n)_ | _O(1)_ | Easy || 186| [Reverse Words in a String II](https://leetcode.com/problems/reverse-words-in-a-string-ii/) |[C++](./C++/reverse-words-in-a-string-ii.cpp) [Python](./Python/reverse-words-in-a-string-ii.py) | _O(n)_ | _O(1)_ | Medium | 馃摉 | 214| [Shortest Palindrome](https://leetcode.com/problems/shortest-palindrome/) | [C++](./C++/shortest-palindrome.cpp) [Python](./Python/shortest-palindrome.py) | _O(n)_ | _O(n)_ | Hard || `KMP Algorithm` `Manacher's Algorithm` 242| [Valid Anagram](https://leetcode.com/problems/valid-anagram/)| [C++](./C++/valid-anagram.cpp) [Python](./Python/valid-anagram.py) | _O(n)_ | _O(1)_ | Easy | LintCode | 271| [Encode and Decode Strings](https://leetcode.com/problems/encode-and-decode-strings/) | [C++](./C++/encode-and-decode-strings.cpp) [Python](./Python/encode-and-decode-strings.py) | _O(n)_ | _O(1)_ | Medium | 馃摉 | 273| [Integer to English Words](https://leetcode.com/problems/integer-to-english-words/) | [C++](./C++/integer-to-english-words.cpp) [Python](./Python/integer-to-english-words.py) | _O(logn)_ | _O(1)_ | Hard | | 306| [Addictive Number](https://leetcode.com/problems/additive-number/) | [C++](./C++/additive-number.cpp) [Python](./Python/additive-number.py) | _O(n^3)_ | _O(n)_ | Medium | | 383| [Ransom Note](https://leetcode.com/problems/ransom-note/) | [C++](./C++/ransom-note.cpp) [Python](./Python/ransom-note.py) | _O(n)_ | _O(1)_ | Easy | EPI | 405| [Convert a Number to Hexadecimal](https://leetcode.com/problems/convert-a-number-to-hexadecimal/) | [C++](./C++/convert-a-number-to-hexadecimal.cpp) [Python](./Python/convert-a-number-to-hexadecimal.py) | _O(n)_ | _O(1)_ | Easy | | 408| [Valid Word Abbreviation](https://leetcode.com/problems/valid-word-abbreviation/) | [C++](./C++/valid-word-abbreviation.cpp) [Python](./Python/valid-word-abbreviation.py) | _O(n)_ | _O(1)_ | Easy | 馃摉 | 415| [Add Strings](https://leetcode.com/problems/add-strings/) | [C++](./C++/add-strings.cpp) [Python](./Python/add-strings.py) | _O(n)_ | _O(1)_ | Easy | | 420| [Strong Password Checker](https://leetcode.com/problems/strong-password-checker/) | [C++](./C++/strong-password-checker.cpp) [Python](./Python/strong-password-checker.py) | _O(n)_ | _O(1)_ | Hard | | 434| [Number of Segments in a String](https://leetcode.com/problems/number-of-segments-in-a-string/) | [C++](./C++/number-of-segments-in-a-string.cpp) [Python](./Python/number-of-segments-in-a-string.py) | _O(n)_ | _O(1)_ | Easy | | 459| [Repeated Substring Pattern](https://leetcode.com/problems/repeated-substring-pattern/) | [C++](./C++/repeated-substring-pattern.cpp) [Python](./Python/repeated-substring-pattern.py) | _O(n)_ | _O(n)_ | Easy || `KMP Algorithm` | 468| [Validate IP Address](https://leetcode.com/problems/validate-ip-address/) | [C++](./C++/validate-ip-address.cpp) [Python](./Python/validate-ip-address.py) | _O(1)_ | _O(1)_ | Medium | | ## Linked List | # | Title | Solution | Time | Space | Difficulty | Tag | Note| |-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----| 2| [Add Two Numbers](https://leetcode.com/problems/add-two-numbers/) | [C++](./C++/add-two-numbers.cpp) [Python](./Python/add-two-numbers.py) | _O(n)_ | _O(1)_ | Medium || 21| [Merge Two Sorted Lists](https://leetcode.com/problems/merge-two-sorted-lists/)| [C++](./C++/merge-two-sorted-lists.cpp) [Python](./Python/merge-two-sorted-lists.py) | _O(n)_ | _O(1)_ | Easy || 23| [Merge k Sorted Lists](https://leetcode.com/problems/merge-k-sorted-lists/) | [C++](./C++/merge-k-sorted-lists.cpp) [Python](./Python/merge-k-sorted-lists.py) | _O(nlogk)_| _O(1)_| Hard | | Heap, Divide and Conquer 24| [Swap Nodes in Pairs](https://leetcode.com/problems/swap-nodes-in-pairs/)| [C++](./C++/swap-nodes-in-pairs.cpp) [Python](./Python/swap-nodes-in-pairs.py) | _O(n)_ | _O(1)_ | Easy || 25| [Reverse Nodes in k-Group](https://leetcode.com/problems/reverse-nodes-in-k-group/)| [C++](./C++/reverse-nodes-in-k-group.cpp) [Python](./Python/reverse-nodes-in-k-group.py) | _O(n)_ | _O(1)_ | Hard || 61| [Rotate List](https://leetcode.com/problems/rotate-list/)| [C++](./C++/rotate-list.cpp) [Python](./Python/rotate-list.py) | _O(n)_ | _O(1)_ | Medium || 82| [Remove Duplicates from Sorted List II](https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii/)| [C++](./C++/remove-duplicates-from-sorted-list-ii.cpp) [Python](./Python/remove-duplicates-from-sorted-list-ii.py) | _O(n)_ | _O(1)_ | Medium || 83| [Remove Duplicates from Sorted List](https://leetcode.com/problems/remove-duplicates-from-sorted-list/)| [C++](./C++/remove-duplicates-from-sorted-list.cpp) [Python](./Python/remove-duplicates-from-sorted-list.py) | _O(n)_ | _O(1)_ | Easy || 92| [Reverse Linked List II](https://leetcode.com/problems/reverse-linked-list-ii/)| [C++](./C++/reverse-linked-list-ii.cpp) [Python](./Python/reverse-linked-list-ii.py) | _O(n)_ | _O(1)_ | Medium || 138| [Copy List with Random Pointer](https://leetcode.com/problems/copy-list-with-random-pointer/) | [C++](./C++/copy-list-with-random-pointer.cpp) [Python](./Python/copy-list-with-random-pointer.py) | _O(n)_ | _O(1)_ | Hard || 160| [Intersection of Two Linked Lists](https://leetcode.com/problems/intersection-of-two-linked-lists/)| [C++](./C++/intersection-of-two-linked-lists.cpp) [Python](./Python/intersection-of-two-linked-lists.py) | _O(m + n)_ | _O(1)_ | Easy || 203| [Remove Linked List Elements](https://leetcode.com/problems/remove-linked-list-elements/)| [C++](./C++/remove-linked-list-elements.cpp) [Python](./Python/remove-linked-list-elements.py) | _O(n)_ | _O(1)_ | Easy || 206| [Reverse Linked List](https://leetcode.com/problems/reverse-linked-list/)| [C++](./C++/reverse-linked-list.cpp) [Python](./Python/reverse-linked-list.py) | _O(n)_ | _O(1)_ | Easy || 234| [Palindrome Linked List](https://leetcode.com/problems/palindrome-linked-list/)| [C++](./C++/palindrome-linked-list.cpp) [Python](./Python/palindrome-linked-list.py) | _O(n)_ | _O(1)_ | Easy || 237| [Delete Node in a Linked List](https://leetcode.com/problems/delete-node-in-a-linked-list/)| [C++](./C++/delete-node-in-a-linked-list.cpp) [Python](./Python/delete-node-in-a-linked-list.py) | _O(1)_ | _O(1)_ | Easy | LintCode | 328| [Odd Even Linked List](https://leetcode.com/problems/odd-even-linked-list/)| [C++](./C++/odd-even-linked-list.cpp) [Python](./Python/odd-even-linked-list.py) | _O(n)_ | _O(1)_ | Medium | | 369| [Plus One Linked List](https://leetcode.com/problems/plus-one-linked-list/)| [C++](./C++/plus-one-linked-list.cpp) [Python](./Python/plus-one-linked-list.py) | _O(n)_ | _O(1)_ | Medium | 馃摉 | Two Pointers | 445| [Add Two Numbers II](https://leetcode.com/problems/add-two-numbers-ii/)| [C++](./C++/add-two-numbers-ii.cpp) [Python](./Python/add-two-numbers-ii.py) | _O(m + n)_ | _O(m + n)_ | Medium ||| ## Stack | # | Title | Solution | Time | Space | Difficulty | Tag | Note| |-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----| 20| [Valid Parentheses](https://leetcode.com/problems/valid-parentheses/)| [C++](./C++/valid-parentheses.cpp) [Python](./Python/valid-parentheses.py) | _O(n)_ | _O(n)_ | Easy || 32| [Longest Valid Parentheses](https://leetcode.com/problems/longest-valid-parentheses/)| [C++](./C++/longest-valid-parentheses.cpp) [Python](./Python/longest-valid-parentheses.py) | _O(n)_ | _O(1)_ | Hard || 71| [Simplify Path](https://leetcode.com/problems/simplify-path/)| [C++](./C++/simplify-path.cpp) [Python](./Python/simplify-path.py) | _O(n)_ | _O(n)_ | Medium || 84| [Largest Rectangle in Histogram](https://leetcode.com/problems/largest-rectangle-in-histogram/) | [C++](./C++/largest-rectangle-in-histogram.cpp) [Python](./Python/largest-rectangle-in-histogram.py) | _O(n)_ | _O(n)_ | Hard || Ascending Stack, DP 85| [Maximal Rectangle](https://leetcode.com/problems/maximal-rectangle/)| [C++](./C++/maximal-rectangle.cpp) [Python](./Python/maximal-rectangle.py)| _O(m * n)_ | _O(n)_ | Hard | EPI | Ascending Stack 101| [Symmetric Tree](https://leetcode.com/problems/symmetric-tree/)| [C++](./C++/symmetric-tree.cpp) [Python](./Python/symmetric-tree.py) | _O(n)_ | _O(h)_ | Easy || 150| [Evaluate Reverse Polish Notation](https://leetcode.com/problems/evaluate-reverse-polish-notation/)| [C++](./C++/evaluate-reverse-polish-notation.cpp) [Python](./Python/evaluate-reverse-polish-notation.py)| _O(n)_| _O(n)_| Medium || 155| [Min Stack](https://leetcode.com/problems/min-stack/) | [C++](./C++/min-stack.cpp) [Python](./Python/min-stack.py) | _O(n)_ | _O(1)_ | Easy || 173| [Binary Search Tree Iterator](https://leetcode.com/problems/binary-search-tree-iterator/) | [C++](./C++/binary-search-tree-iterator.cpp) [Python](./Python/binary-search-tree-iterator.py) | _O(1)_| _O(h)_| Medium || 224| [Basic Calculator](https://leetcode.com/problems/basic-calculator/) | [C++](./C++/basic-calculator.cpp) [Python](./Python/basic-calculator.py) | _O(n)_| _O(n)_| Hard || 227| [Basic Calculator II](https://leetcode.com/problems/basic-calculator-ii/) | [C++](./C++/basic-calculator-ii.cpp) [Python](./Python/basic-calculator-ii.py) | _O(n)_| _O(n)_| Medium || 232| [Implement Queue using Stacks](https://leetcode.com/problems/implement-queue-using-stacks/) | [C++](./C++/implement-queue-using-stacks.cpp) [Python](./Python/implement-queue-using-stacks.py) | _O(1), amortized_| _O(n)_| Easy | EPI, LintCode | 255| [Verify Preorder Sequence in Binary Search Tree](https://leetcode.com/problems/verify-preorder-sequence-in-binary-search-tree/) | [C++](./C++/verify-preorder-sequence-in-binary-search-tree.cpp) [Python](./Python/verify-preorder-sequence-in-binary-search-tree.py) | _O(n)_| _O(1)_| Medium |馃摉|| 272| [Closest Binary Search Tree Value II](https://leetcode.com/problems/closest-binary-search-tree-value-ii/) | [C++](./C++/closest-binary-search-tree-value-ii.cpp) [Python](./Python/closest-binary-search-tree-value-ii.py) | _O(h + k)_| _O(h)_| Hard |馃摉|| 331| [Verify Preorder Serialization of a Binary Tree](https://leetcode.com/problems/verify-preorder-serialization-of-a-binary-tree/) | [C++](./C++/verify-preorder-serialization-of-a-binary-tree.cpp) [Python](./Python/verify-preorder-serialization-of-a-binary-tree.py) | _O(n)_| _O(1)_| Medium ||| 341| [Flatten Nested List Iterator](https://leetcode.com/problems/flatten-nested-list-iterator/)| [C++](./C++/flatten-nested-list-iterator.cpp) [Python](./Python/flatten-nested-list-iterator.py) | _O(n)_ | _O(h)_ | Medium |馃摉| Iterator | 385| [Mini Parser](https://leetcode.com/problems/mini-parser/)| [C++](./C++/mini-parser.cpp) [Python](./Python/mini-parser.py) | _O(n)_ | _O(h)_ | Medium ||| 394| [Decode String](https://leetcode.com/problems/decode-string/)| [C++](./C++/decode-string.cpp) [Python](./Python/decode-string.py) | _O(n)_ | _O(h)_ | Medium ||| 439| [Ternary Expression Parser](https://leetcode.com/problems/ternary-expression-parser/) | [C++](./C++/ternary-expression-parser.cpp) [Python](./Python/ternary-expression-parser.py) | _O(n)_ | _O(1)_ | Medium |馃摉| 456| [132 Pattern](https://leetcode.com/problems/132-pattern/) | [C++](./C++/132-pattern.cpp) [Python](./Python/132-pattern.py) | _O(n)_ | _O(n)_ | Medium || ## Queue | # | Title | Solution | Time | Space | Difficulty | Tag | Note| |-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----| 239| [Sliding Window Maximum](https://leetcode.com/problems/sliding-window-maximum/)| [C++](./C++/sliding-window-maximum.cpp) [Python](./Python/sliding-window-maximum.py) | _O(n)_ | _O(k)_ | Hard | EPI, LintCode | 281| [Zigzag Iterator](https://leetcode.com/problems/zigzag-iterator/)| [C++](./C++/zigzag-iterator.cpp) [Python](./Python/zigzag-iterator.py) | _O(n)_ | _O(k)_ | Medium |馃摉|| 346| [Moving Average from Data Stream](https://leetcode.com/problems/moving-average-from-data-stream/)| [C++](./C++/moving-average-from-data-stream.cpp) [Python](./Python/moving-average-from-data-stream.py) | _O(1)_ | _O(w)_ | Easy |馃摉|| ## Heap | # | Title | Solution | Time | Space | Difficulty | Tag | Note| |-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----| 264| [Ugly Number II](https://leetcode.com/problems/ugly-number-ii/) | [C++](./C++/ugly-number-ii.cpp) [Python](./Python/ugly-number-ii.py) | _O(n)_ | _O(1)_ | Medium | CTCI, LintCode | BST, Heap | 295| [Find Median from Data Stream](https://leetcode.com/problems/find-median-from-data-stream/) | [C++](./C++/find-median-from-data-stream.cpp) [Python](./Python/find-median-from-data-stream.py) | _O(nlogn)_ | _O(n)_ | Hard | EPI, LintCode | BST, Heap | 313| [Super Ugly Number](https://leetcode.com/problems/super-ugly-number/) | [C++](./C++/super-ugly-number.cpp) [Python](./Python/super-ugly-number.py) | _O(n * k)_ | _O(n + k)_ | Medium || BST, Heap | 358| [Rearrange String k Distance Apart](https://leetcode.com/problems/rearrange-string-k-distance-apart/)| [C++](./C++/rearrange-string-k-distance-apart.cpp) [Python](./Python/rearrange-string-k-distance-apart.py) | _O(n)_ | _O(n)_ | Hard |馃摉| Greedy, Heap | 373 | [Find K Pairs with Smallest Sums](https://leetcode.com/problems/find-k-pairs-with-smallest-sums/) | [C++](./C++/find-k-pairs-with-smallest-sums.cpp) [Python](./Python/find-k-pairs-with-smallest-sums.py) | _O(k * log(min(n, m, k)))_ | _O(min(n, m, k))_ | Medium ||| 378 | [Kth Smallest Element in a Sorted Matrix](https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix/) | [C++](./C++/kth-smallest-element-in-a-sorted-matrix.cpp) [Python](./Python/kth-smallest-element-in-a-sorted-matrix.py) | _O(k * log(min(n, m, k)))_ | _O(min(n, m, k))_ | Medium | LintCode || 407 | [Trapping Rain Water II](https://leetcode.com/problems/trapping-rain-water-ii/) | [C++](./C++/trapping-rain-water-ii.cpp) [Python](./Python/trapping-rain-water-ii.py) | _O(m * n * (logm + logn))_ | _O(m * n)_ | Hard | LintCode || ## Tree | # | Title | Solution | Time | Space | Difficulty | Tag | Note| |-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----| 94 | [Binary Tree Inorder Traversal](https://leetcode.com/problems/binary-tree-inorder-traversal/) | [C++](./C++/binary-tree-inorder-traversal.cpp) [Python](./Python/binary-tree-inorder-traversal.py) | _O(n)_| _O(1)_| Medium || `Morris Traversal` | 99 | [Recover Binary Search Tree](https://leetcode.com/problems/recover-binary-search-tree/) | [C++](./C++/recover-binary-search-tree.cpp) [Python](./Python/recover-binary-search-tree.py) | _O(n)_| _O(1)_| Hard || `Morris Traversal` 144 | [Binary Tree Preorder Traversal](https://leetcode.com/problems/binary-tree-preorder-traversal/) | [C++](./C++/binary-tree-preorder-traversal.cpp) [Python](./Python/binary-tree-preorder-traversal.py) | _O(n)_| _O(1)_| Medium || `Morris Traversal` 145 | [Binary Tree Postorder Traversal](https://leetcode.com/problems/binary-tree-postorder-traversal/) | [C++](./C++/binary-tree-postorder-traversal.cpp) [Python](./Python/binary-tree-postorder-traversal.py) | _O(n)_| _O(1)_| Hard || `Morris Traversal` 208 | [Implement Trie (Prefix Tree)](https://leetcode.com/problems/implement-trie-prefix-tree/) | [C++](./C++/implement-trie-prefix-tree.cpp) [Python](./Python/implement-trie-prefix-tree.py) | _O(n)_ | _O(1)_ | Medium || Trie 211 | [Add and Search Word - Data structure design](https://leetcode.com/problems/add-and-search-word-data-structure-design/) | [C++](./C++/add-and-search-word-data-structure-design.cpp) [Python](./Python/add-and-search-word-data-structure-design.py) | _O(min(n, h))_ | _O(min(n, h))_ | Medium || Trie, DFS 226| [Invert Binary Tree](https://leetcode.com/problems/invert-binary-tree/) | [C++](./C++/invert-binary-tree.cpp) [Python](./Python/invert-binary-tree.py) | _O(n)_ | _O(h)_, _O(w)_ | Easy || 297 | [Serialize and Deserialize Binary Tree](https://leetcode.com/problems/serialize-and-deserialize-binary-tree/) | [C++](./C++/serialize-and-deserialize-binary-tree.cpp) [Python](./Python/serialize-and-deserialize-binary-tree.py) | _O(n)_ | _O(h)_ | Hard | LintCode | DFS 307 | [Range Sum Query - Mutable](https://leetcode.com/problems/range-sum-query-mutable/) | [C++](./C++/range-sum-query-mutable.cpp) [Python](./Python/range-sum-query-mutable.py) | ctor: _O(n)_, update: _O(logn)_, query: _O(logn)_ | _O(n)_ | Medium | LintCode | DFS, Segment Tree, BIT 308 | [Range Sum Query 2D - Mutable](https://leetcode.com/problems/range-sum-query-2d-mutable/) | [C++](./C++/range-sum-query-2d-mutable.cpp) [Python](./Python/range-sum-query-2d-mutable.py) | ctor: _O(m * n)_, update: _O(logm + logn)_, query: _O(logm + logn)_ | _O(m * n)_ | Hard | 馃摉 | DFS, Segment Tree, BIT 315|[Count of Smaller Numbers After Self](https://leetcode.com/problems/count-of-smaller-numbers-after-self/)| [C++](./C++/count-of-smaller-numbers-after-self.cpp) [Python](./Python/count-of-smaller-numbers-after-self.py)| _O(nlogn)_ | _O(n)_ | Hard | LintCode | BST, BIT, Divide and Conquer | ## Hash Table | # | Title | Solution | Time | Space | Difficulty | Tag | Note| |-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----| 1| [Two Sum](https://leetcode.com/problems/two-sum/) | [C++](./C++/two-sum.cpp) [Python](./Python/two-sum.py) | _O(n)_ | _O(n)_ | Easy || 3| [Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters/) | [C++](./C++/longest-substring-without-repeating-characters.cpp) [Python](./Python/longest-substring-without-repeating-characters.py) | _O(n)_ | _O(1)_ | Medium || 30| [Substring with Concatenation of All Words](https://leetcode.com/problems/substring-with-concatenation-of-all-words/) | [C++](./C++/substring-with-concatenation-of-all-words.cpp) [Python](./Python/substring-with-concatenation-of-all-words.py) | _O(m * n * k)_ | _O(n * k)_ | Hard || 36| [Valid Sudoku](https://leetcode.com/problems/valid-sudoku/) | [C++](./C++/valid-sudoku.cpp) [Python](./Python/valid-sudoku.py) | _O(9^2)_ | _O(9)_ | Easy || 49| [Group Anagrams](https://leetcode.com/problems/anagrams/) | [C++](./C++/anagrams.cpp) [Python](./Python/anagrams.py) | _O(n * glogg)_ | _O(n)_ | Medium || 76| [Minimum Window Substring](https://leetcode.com/problems/minimum-window-substring/) | [C++](./C++/minimum-window-substring.cpp) [Python](./Python/minimum-window-substring.py) | _O(n)_ | _O(k)_ | Hard || 149| [Max Points on a Line](https://leetcode.com/problems/max-points-on-a-line/) | [C++](./C++/max-points-on-a-line.cpp) [Python](./Python/max-points-on-a-line.py) | _O(n^2)_ | _O(n)_ | Hard || 159| [Longest Substring with At Most Two Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-two-distinct-characters/)| [C++](./C++/longest-substring-with-at-most-two-distinct-characters.cpp) [Python](./Python/longest-substring-with-at-most-two-distinct-characters.py) | _O(n)_ | _O(1)_ | Hard |馃摉| 170| [Two Sum III - Data structure design](https://leetcode.com/problems/two-sum-iii-data-structure-design/) | [C++](./C++/two-sum-iii-data-structure-design.cpp) [Python](./Python/two-sum-iii-data-structure-design.py) | _O(n)_ | _O(n)_ | Easy | 馃摉 | 187| [Repeated DNA Sequences](https://leetcode.com/problems/repeated-dna-sequences/) | [Python](./Python/repeated-dna-sequences.py) | _O(n)_ | _O(n)_ | Medium || 202| [Happy Number](https://leetcode.com/problems/happy-number/) | [C++](./C++/happy-number.cpp) [Python](./Python/happy-number.py) | _O(k)_ | _O(k)_ | Easy || 204| [Count Primes](https://leetcode.com/problems/count-primes/) | [C++](./C++/count-primes.cpp) [Python](./Python/count-primes.py) | _O(n)_ | _O(n)_ | Easy || 205| [Isomorphic Strings](https://leetcode.com/problems/isomorphic-strings/) | [C++](./C++/isomorphic-strings.cpp) [Python](./Python/isomorphic-strings.py) | _O(n)_ | _O(1)_ | Easy || 217| [Contains Duplicate](https://leetcode.com/problems/contains-duplicate/) | [C++](./C++/contains-duplicate.cpp) [Python](./Python/contains-duplicate.py) | _O(n)_ | _O(n)_ | Easy || 219| [Contains Duplicate II](https://leetcode.com/problems/contains-duplicate-ii/) | [C++](./C++/contains-duplicate-ii.cpp) [Python](./Python/contains-duplicate-ii.py) | _O(n)_ | _O(n)_ | Easy || 244| [Shortest Word Distance II](https://leetcode.com/problems/shortest-word-distance-ii/) | [C++](./C++/shortest-word-distance-ii.cpp) [Python](./Python/shortest-word-distance-ii.py) | ctor: _O(n)_, lookup: _O(a + b)_ | _O(n)_ | Medium |馃摉|| 246| [Strobogrammatic Number](https://leetcode.com/problems/strobogrammatic-number/) | [C++](./C++/strobogrammatic-number.cpp) [Python](./Python/strobogrammatic-number.py) | _O(n)_ | _O(1)_ | Easy |馃摉|| 249| [Group Shifted Strings](https://leetcode.com/problems/group-shifted-strings/) | [C++](./C++/group-shifted-strings.cpp) [Python](./Python/group-shifted-strings.py) | _O(nlogn)_ | _O(n)_ | Easy |馃摉|| 266| [Palindrome Permutation](https://leetcode.com/problems/palindrome-permutation/) | [C++](./C++/palindrome-permutation.cpp) [Python](./Python/palindrome-permutation.py) | _O(n)_ | _O(1)_ | Easy |馃摉|| 288| [Unique Word Abbreviation](https://leetcode.com/problems/unique-word-abbreviation/) | [C++](./C++/unique-word-abbreviation.cpp) [Python](./Python/unique-word-abbreviation.py) | ctor: _O(n)_, lookup: _O(1)_ | _O(k)_ | Easy |馃摉|| 290| [Word Pattern](https://leetcode.com/problems/word-pattern/) | [C++](./C++/word-pattern.cpp) [Python](./Python/word-pattern.py) | _O(n)_ | _O(c)_ | Easy | variant of [Isomorphic Strings](https://leetcode.com/problems/isomorphic-strings/) || 299| [Bulls and Cows](https://leetcode.com/problems/bulls-and-cows/) | [C++](./C++/bulls-and-cows.cpp) [Python](./Python/bulls-and-cows.py) | _O(n)_ | _O(1)_ | Easy ||| 305| [Number of Islands II](https://leetcode.com/problems/number-of-islands-ii/) | [C++](./C++/number-of-islands-ii.cpp) [Python](./Python/number-of-islands-ii.py) | _O(k)_ | _O(k)_| Hard | LintCode, 馃摉 | Union Find 314| [Binary Tree Vertical Order Traversal](https://leetcode.com/problems/binary-tree-vertical-order-traversal/) | [C++](./C++/binary-tree-vertical-order-traversal.cpp) [Python](./Python/binary-tree-vertical-order-traversal.py) | _O(n)_ | _O(n)_| Medium | 馃摉 | BFS 323| [Number of Connected Components in an Undirected Graph](https://leetcode.com/problems/number-of-connected-components-in-an-undirected-graph/) | [C++](./C++/number-of-connected-components-in-an-undirected-graph.cpp) [Python](./Python/number-of-connected-components-in-an-undirected-graph.py) | _O(n)_ | _O(n)_| Medium | 馃摉 | Union Find 325| [Maximum Size Subarray Sum Equals k](https://leetcode.com/problems/maximum-size-subarray-sum-equals-k/) | [C++](./C++/maximum-size-subarray-sum-equals-k.cpp) [Python](./Python/maximum-size-subarray-sum-equals-k.py) | _O(n)_ | _O(n)_| Medium | 馃摉 | 336| [Palindrome Pairs](https://leetcode.com/problems/palindrome-pairs/) | [C++](./C++/palindrome-pairs.cpp) [Python](./Python/palindrome-pairs.py) | _O(n * k^2)_ | _O(n * k)_ | Hard | | | 340| [Longest Substring with At Most K Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-k-distinct-characters/)| [C++](./C++/longest-substring-with-at-most-k-distinct-characters.cpp) [Python](./Python/longest-substring-with-at-most-k-distinct-characters.py) | _O(n)_ | _O(1)_ | Hard |馃摉| 356| [Line Reflection](https://leetcode.com/problems/line-reflection/) | [C++](./C++/line-reflection.cpp) [Python](./Python/line-reflection.py) | _O(n)_| _O(n)_| Medium |馃摉| Hash, Two Pointers | 387| [First Unique Character in a String](https://leetcode.com/problems/first-unique-character-in-a-string/) | [C++](./C++/first-unique-character-in-a-string.cpp) [Python](./Python/first-unique-character-in-a-string.py) | _O(n)_| _O(n)_| Easy ||| 388| [Longest Absolute File Path](https://leetcode.com/problems/longest-absolute-file-path/) | [C++](./C++/longest-absolute-file-path.cpp) [Python](./Python/longest-absolute-file-path.py) | _O(n)_| _O(d)_| Medium || Stack | 409| [Longest Palindrome](https://leetcode.com/problems/longest-palindrome/) | [C++](./C++/longest-palindrome.cpp) [Python](./Python/longest-palindrome.py) | _O(n)_| _O(1)_| Easy ||| 424| [Longest Repeating Character Replacement](https://leetcode.com/problems/longest-repeating-character-replacement/) | [C++](./C++/longest-repeating-character-replacement.cpp) [Python](./Python/longest-repeating-character-replacement.py) | _O(n)_| _O(1)_| Medium ||| 438| [Find All Anagrams in a String](https://leetcode.com/problems/find-all-anagrams-in-a-string/) | [C++](./C++/find-all-anagrams-in-a-string.cpp) [Python](./Python/find-all-anagrams-in-a-string.py) | _O(n)_ | _O(1)_ | Easy || 447| [Number of Boomerangs](https://leetcode.com/problems/number-of-boomerangs/) | [C++](./C++/number-of-boomerangs.cpp) [Python](./Python/number-of-boomerangs.py) | _O(n^2)_ | _O(n)_ | Easy || 454| [4Sum II](https://leetcode.com/problems/4sum-ii/) | [C++](./C++/4sum-ii.cpp) [Python](./Python/4sum-ii.py) | _O(n^2)_ | _O(n^2)_ | Medium || 473| [Matchsticks to Square](https://leetcode.com/problems/matchsticks-to-square/) | [C++](./C++/matchsticks-to-square.cpp) [Python](./Python/matchsticks-to-square.py) | _O(n * s * 2^n)_ | _O(n * (2^n + s))_ | Medium || ## Data Structure | # | Title | Solution | Time | Space | Difficulty | Tag | Note| |-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----| 146| [LRU Cache](https://leetcode.com/problems/lru-cache/) | [C++](./C++/lru-cache.cpp) [Python](./Python/lru-cache.py) | _O(1)_ | _O(k)_ | Hard || 225| [Implement Stack using Queues](https://leetcode.com/problems/implement-stack-using-queues/) | [C++](./C++/implement-stack-using-queues.cpp) [Python](./Python/implement-stack-using-queues.py) | push: _O(n)_, pop: _O(1)_, top: _O(1)_ | _O(n)_ | Easy || ## Math | # | Title | Solution | Time | Space | Difficulty | Tag | Note| |-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----| 7| [Reverse Integer](https://leetcode.com/problems/reverse-integer/) | [C++](./C++/reverse-integer.cpp) [Python](./Python/reverse-integer.py) | _O(1)_ | _O(1)_ | Easy || 9| [Palindrome Number](https://leetcode.com/problems/palindrome-number/) | [C++](./C++/palindrome-number.cpp) [Python](./Python/palindrome-number.py) | _O(1)_ | _O(1)_ | Easy || 12| [Integer to Roman](https://leetcode.com/problems/integer-to-roman/) | [C++](./C++/integer-to-roman.cpp) [Python](./Python/integer-to-roman.py) | _O(n)_ | _O(1)_ | Medium || 13| [Roman to Integer](https://leetcode.com/problems/roman-to-integer/) | [C++](./C++/roman-to-integer.cpp) [Python](./Python/roman-to-integer.py) | _O(n)_ | _O(1)_ | Easy || 29| [Divide Two Integers](https://leetcode.com/problems/divide-two-integers/) | [C++](./C++/divide-two-integers.cpp) [Python](./Python/divide-two-integers.py) | _O(1)_ | _O(1)_ | Medium || 50| [Pow(x, n)](https://leetcode.com/problems/powx-n/) | [C++](./C++/powx-n.cpp) [Python](./Python/powx-n.py) | _O(1)_ | _O(1)_ | Medium || 60| [Permutation Sequence](https://leetcode.com/problems/permutation-sequence/) | [C++](./C++/permutation-sequence.cpp) [Python](./Python/permutation-sequence.py) | _O(n^2)_ | _O(n)_ | Medium || `Cantor Ordering` 65| [Valid Number](https://leetcode.com/problems/valid-number/) | [C++](./C++/valid-number.cpp) [Python](./Python/valid-number.py) | _O(n)_ | _O(1)_ | Hard || `Automata` 89| [Gray Code](https://leetcode.com/problems/gray-code/) | [C++](./C++/gray-code.cpp) [Python](./Python/gray-code.py) | _O(2^n)_ | _O(1)_ | Medium || 166| [Fraction to Recurring Decimal](https://leetcode.com/problems/fraction-to-recurring-decimal/) | [C++](./C++/fraction-to-recurring-decimal.cpp) [Python](./Python/fraction-to-recurring-decimal.py) | _O(logn)_ | _O(1)_ | Medium || 168| [Excel Sheet Column Title](https://leetcode.com/problems/excel-sheet-column-title/) | [C++](./C++/excel-sheet-column-title.cpp) [Python](./Python/excel-sheet-column-title.py) | _O(logn)_ | _O(1)_ | Easy || 171| [Excel Sheet Column Number](https://leetcode.com/problems/excel-sheet-column-number/) | [C++](./C++/excel-sheet-column-number.cpp) [Python](./Python/excel-sheet-column-number.py) | _O(n)_ | _O(1)_ | Easy || 172| [Factorial Trailing Zeroes](https://leetcode.com/problems/factorial-trailing-zeroes/) | [C++](./C++/factorial-trailing-zeroes.cpp) [Python](./Python/factorial-trailing-zeroes.py) | _O(1)_ | _O(1)_ | Easy || 223| [Rectangle Area](https://leetcode.com/problems/rectangle-area/) | [C++](./C++/rectangle-area.cpp) [Python](./Python/rectangle-area.py) | _O(1)_ | _O(1)_ | Easy || 233| [Number of Digit One](https://leetcode.com/problems/number-of-digit-one/) | [C++](./C++/number-of-digit-one.cpp) [Python](./Python/number-of-digit-one.py) | _O(1)_ | _O(1)_ | Hard | CTCI, LintCode| 248| [Strobogrammatic Number III](https://leetcode.com/problems/strobogrammatic-number-iii/) | [C++](./C++/strobogrammatic-number-iii.cpp) [Python](./Python/strobogrammatic-number-iii.py) | _O(5^(n/2))_ | _O(n)_ | Hard |馃摉|| 258| [Add Digits](https://leetcode.com/problems/add-digits/) | [C++](./C++/add-digits.cpp) [Python](./Python/add-digits.py) | _O(1)_ | _O(1)_ | Easy ||| 263| [Ugly Number](https://leetcode.com/problems/ugly-number/) | [C++](./C++/ugly-number.cpp) [Python](./Python/ugly-number.py) | _O(1)_ | _O(1)_ | Easy ||| 292| [Nim Game](https://leetcode.com/problems/nim-game/) | [C++](./C++/nim-game.cpp) [Python](./Python/nim-game.py) | _O(1)_ | _O(1)_ | Easy | LintCode || 319 | [Bulb Switcher](https://leetcode.com/problems/bulb-switcher/) | [C++](./C++/bulb-switcher.cpp) [Python](./Python/bulb-switcher.py) | _O(1)_ | _O(1)_ | Medium ||| 326 | [Power of Three](https://leetcode.com/problems/power-of-three/) | [C++](./C++/power-of-three.cpp) [Python](./Python/power-of-three.py) | _O(1)_ | _O(1)_ | Easy ||| 335 | [Self Crossing](https://leetcode.com/problems/self-crossing/) | [C++](./C++/self-crossing.cpp) [Python](./Python/self-crossing.py) | _O(n)_ | _O(1)_ | Hard ||| 338 | [Counting Bits](https://leetcode.com/problems/counting-bits/) | [C++](./C++/counting-bits.cpp) [Python](./Python/counting-bits.py) | _O(n)_ | _O(n)_ | Medium ||| 343 | [Integer Break](https://leetcode.com/problems/integer-break/) | [C++](./C++/integer-break.cpp) [Python](./Python/integer-break.py) | _O(logn)_ | _O(1)_ | Medium || Tricky, DP | 365 | [Water and Jug Problem](https://leetcode.com/problems/water-and-jug-problem/) | [C++](./C++/water-and-jug-problem.cpp) [Python](./Python/water-and-jug-problem.py) | _O(logn)_ | _O(1)_ | Medium || Euclidean Algorithm | 372 | [Super Pow](https://leetcode.com/problems/super-pow/) | [C++](./C++/super-pow.cpp) [Python](./Python/super-pow.py) | _O(n)_ | _O(1)_ | Medium ||| 382 | [Linked List Random Node](https://leetcode.com/problems/linked-list-random-node/) | [C++](./C++/linked-list-random-node.cpp) [Python](./Python/linked-list-random-node.py) | _O(n)_ | _O(1)_ | Medium || `Reservoir Sampling` | 386 | [Lexicographical Numbers](https://leetcode.com/problems/lexicographical-numbers/) | [C++](./C++/lexicographical-numbers.cpp) [Python](./Python/lexicographical-numbers.py) | _O(n)_ | _O(1)_ | Medium ||| 390 | [Elimination Game](https://leetcode.com/problems/elimination-game/) | [C++](./C++/elimination-game.cpp) [Python](./Python/elimination-game.py) | _O(logn)_ | _O(1)_ | Medium || 391 | [Perfect Rectangle](https://leetcode.com/problems/perfect-rectangle/) | [C++](./C++/perfect-rectangle.cpp) [Python](./Python/perfect-rectangle.py) | _O(n)_ | _O(n)_ | Hard | | 398 | [Random Pick Index](https://leetcode.com/problems/random-pick-index/) | [C++](./C++/random-pick-index.cpp) [Python](./Python/random-pick-index.py) | _O(n)_ | _O(1)_ | Medium || `Reservoir Sampling` | 400 | [Nth Digit](https://leetcode.com/problems/nth-digit/) | [C++](./C++/nth-digit.cpp) [Python](./Python/nth-digit.py) | _O(logn)_ | _O(1)_ | Easy ||| 413 | [Arithmetic Slices](https://leetcode.com/problems/arithmetic-slices/) | [C++](./C++/arithmetic-slices.cpp) [Python](./Python/arithmetic-slices.py) | _O(n)_ | _O(1)_ | Medium ||| 423 | [Reconstruct Original Digits from English](https://leetcode.com/problems/reconstruct-original-digits-from-english/) | [C++](./C++/reconstruct-original-digits-from-english.cpp) [Python](./Python/reconstruct-original-digits-from-english.py) | _O(n)_ | _O(1)_ | Medium | [GCJ2016 - Round 1B](https://code.google.com/codejam/contest/11254486/dashboard#s=p0)|| 441 | [Arranging Coins](https://leetcode.com/problems/arranging-coins/) | [C++](./C++/arranging-coins.cpp) [Python](./Python/arranging-coins.py) | _O(nlogn)_ | _O(1)_ | Easy || Binary Search| 453 | [Minimum Moves to Equal Array Elements](https://leetcode.com/problems/minimum-number-of-arrows-to-burst-balloons/) | [C++](./C++/minimum-number-of-arrows-to-burst-balloons.cpp) [Python](./Python/minimum-number-of-arrows-to-burst-balloons.py) | _O(n)_ | _O(1)_ | Easy ||| 458 | [Poor Pigs](https://leetcode.com/problems/poor-pigs/) | [C++](./C++/poor-pigs.cpp) [Python](./Python/poor-pigs.py) | _O(n)_ | _O(1)_ | Easy ||| 469 | [Convex Polygon](https://leetcode.com/problems/convex-polygon/) | [C++](./C++/convex-polygon.cpp) [Python](./Python/convex-polygon.py) | _O(n)_ | _O(1)_ | Medium |馃摉|| ## Sort | # | Title | Solution | Time | Space | Difficulty | Tag | Note| |-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----| 56| [Merge Intervals](https://leetcode.com/problems/merge-intervals/)| [C++](./C++/merge-intervals.cpp) [Python](./Python/merge-intervals.py) | _O(nlogn)_ | _O(1)_ | Hard || 57| [Insert Interval](https://leetcode.com/problems/insert-interval/)| [C++](./C++/insert-interval.cpp) [Python](./Python/insert-interval.py) | _O(n)_ | _O(1)_ | Hard || 75| [Sort Colors](https://leetcode.com/problems/sort-colors/) | [C++](./C++/sort-colors.cpp) [Python](./Python/sort-colors.py) | _O(n)_ | _O(1)_ | Medium || Tri Partition 88| [Merge Sorted Array](https://leetcode.com/problems/merge-sorted-array/)| [C++](./C++/merge-sorted-array.cpp) [Python](./Python/merge-sorted-array.py) | _O(n)_ | _O(1)_ | Easy || 147| [Insertion Sort List](https://leetcode.com/problems/insertion-sort-list/)|[C++](./C++/insertion-sort-list.cpp) [Python](./Python/insertion-sort-list.py) | _O(n^2)_ | _O(1)_ | Medium || 148| [Sort List](https://leetcode.com/problems/sort-list/) | [C++](./C++/sort-list.cpp) [Python](./Python/sort-list.py) | _O(nlogn)_ | _O(logn)_ | Medium || 164| [Maximum Gap](https://leetcode.com/problems/maximum-gap/) | [C++](./C++/maximum-gap.cpp) [Python](./Python/maximum-gap.py)| _O(n)_ | _O(n)_ | Hard || Tricky 179| [Largest Number](https://leetcode.com/problems/largest-number/) | [C++](./C++/largest-number.cpp) [Python](./Python/largest-number.py) | _O(nlogn)_ | _O(1)_ | Medium || 218| [The Skyline Problem](https://leetcode.com/problems/the-skyline-problem/) | [C++](./C++/the-skyline-problem.cpp) [Python](./Python/the-skyline-problem.py) | _O(nlogn)_ | _O(n)_ | Hard || Sort, BST| 252| [Meeting Rooms](https://leetcode.com/problems/meeting-rooms/) | [C++](./C++/meeting-rooms.cpp) [Python](./Python/meeting-rooms.py) | _O(nlogn)_ | _O(n)_ | Easy |馃摉| | 253| [Meeting Rooms II](https://leetcode.com/problems/meeting-rooms-ii/) | [C++](./C++/meeting-rooms-ii.cpp) [Python](./Python/meeting-rooms-ii.py) | _O(nlogn)_ | _O(n)_ | Medium |馃摉| | 274| [H-Index](https://leetcode.com/problems/h-index/) | [C++](./C++/h-index.cpp) [Python](./Python/h-index.py) | _O(n)_ | _O(n)_ | Medium || Counting Sort | 280| [Wiggle Sort](https://leetcode.com/problems/wiggle-sort/) | [C++](./C++/wiggle-sort.cpp) [Python](./Python/wiggle-sort.py) | _O(n)_ | _O(1)_ | Medium |馃摉| | 324| [Wiggle Sort II](https://leetcode.com/problems/wiggle-sort-ii/) | [C++](./C++/wiggle-sort-ii.cpp) [Python](./Python/wiggle-sort-ii.py) | _O(n)_ on average | _O(1)_ | Medium | variant of [Sort Colors](https://leetcode.com/problems/sort-colors/) | Tri Partition | 347| [Top K Frequent Elements](https://leetcode.com/problems/top-k-frequent-elements/) | [C++](./C++/top-k-frequent-elements.cpp) [Python](./Python/top-k-frequent-elements.py) | _O(n)_ on average | _O(n)_ | Medium | | Quick Select, Heap | 406| [Queue Reconstruction by Height](https://leetcode.com/problems/queue-reconstruction-by-height/) | [C++](./C++/queue-reconstruction-by-height.cpp) [Python](./Python/queue-reconstruction-by-height.py) | _O(n * sqrt(n))_ | _O(n)_ | Medium | | | 451| [Sort Characters By Frequency](https://leetcode.com/problems/sort-characters-by-frequency/) | [C++](./C++/sort-characters-by-frequency.cpp) [Python](./Python/sort-characters-by-frequency.py) | _O(n)_ | _O(n)_ | Medium | | | ## Two Pointers | # | Title | Solution | Time | Space | Difficulty | Tag | Note| |-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----| 19| [Remove Nth Node From End of List](https://leetcode.com/problems/remove-nth-node-from-end-of-list/)| [C++](./C++/remove-nth-node-from-end-of-list.cpp) [Python](./Python/remove-nth-node-from-end-of-list.py) | _O(n)_ | _O(1)_ | Easy || 86| [Partition List](https://leetcode.com/problems/partition-list/)| [C++](./C++/partition-list.cpp) [Python](./Python/partition-list.py) | _O(n)_ | _O(1)_ | Medium || 141| [Linked List Cycle](https://leetcode.com/problems/linked-list-cycle/)| [C++](./C++/linked-list-cycle.cpp) [Python](./Python/linked-list-cycle.py) | _O(n)_ | _O(1)_ | Easy || 142| [Linked List Cycle II](https://leetcode.com/problems/linked-list-cycle-ii/)| [C++](./C++/linked-list-cycle-ii.cpp) [Python](./Python/linked-list-cycle-ii.py) | _O(n)_ | _O(1)_ | Medium || 143| [Reorder List](https://leetcode.com/problems/reorder-list/)| [C++](./C++/reorder-list.cpp) [Python](./Python/reorder-list.py) | _O(n)_ | _O(1)_ | Medium || 167| [Two Sum II - Input array is sorted](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/) | [C++](./C++/two-sum-ii-input-array-is-sorted.cpp) [Python](./Python/two-sum-ii-input-array-is-sorted.py) | _O(n)_ | _O(1)_ | Medium | | 259 | [3Sum Smaller](https://leetcode.com/problems/3sum-smaller/) | [C++](./C++/3sum-smaller.cpp) [Python](./Python/3sum-smaller.py) | _O(n^2)_ | _O(1)_ | Medium | 馃摉, LintCode | 283 | [Move Zeroes](https://leetcode.com/problems/move-zeroes/) | [C++](./C++/move-zeroes.cpp) [Python](./Python/move-zeroes.py) | _O(n)_ | _O(1)_ | Easy | | 287| [Find the Duplicate Number](https://leetcode.com/problems/find-the-duplicate-number/)| [C++](./C++/find-the-duplicate-number.cpp) [Python](./Python/find-the-duplicate-number.py) | _O(n)_ | _O(1)_ | Hard | | Binary Search, Two Pointers | 344| [Reverse String](https://leetcode.com/problems/reverse-string/) | [C++](./C++/reverse-string.cpp) [Python](./Python/reverse-string.py) | _O(n)_ | _O(1)_ | Easy | | 345| [Reverse Vowels of a String](https://leetcode.com/problems/reverse-vowels-of-a-string/) | [C++](./C++/reverse-vowels-of-a-string.cpp) [Python](./Python/reverse-vowels-of-a-string.py) | _O(n)_ | _O(1)_ | Easy | | 349| [Intersection of Two Arrays](https://leetcode.com/problems/intersection-of-two-arrays/) | [C++](./C++/intersection-of-two-arrays.cpp) [Python](./Python/intersection-of-two-arrays.py) | _O(m + n)_ | _O(min(m, n))_ | Easy | EPI | Hash, Binary Search 350| [Intersection of Two Arrays II](https://leetcode.com/problems/intersection-of-two-arrays-ii/) | [C++](./C++/intersection-of-two-arrays-ii.cpp) [Python](./Python/intersection-of-two-arrays-ii.py) | _O(m + n)_ | _O(1)_ | Easy | EPI | Hash, Binary Search 360| [Sort Transformed Array](https://leetcode.com/problems/sort-transformed-array/) | [C++](./C++/sort-transformed-array.cpp) [Python](./Python/sort-transformed-array.py) | _O(n)_ | _O(1)_ | Medium |馃摉| 457| [Circular Array Loop](https://leetcode.com/problems/circular-array-loop/) | [C++](./C++/circular-array-loop.cpp) [Python](./Python/circular-array-loop.py) | _O(n)_ | _O(1)_ | Medium || ## Recursion | # | Title | Solution | Time | Space | Difficulty | Tag | Note| |-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----| 95| [Unique Binary Search Trees II](https://leetcode.com/problems/unique-binary-search-trees-ii/) | [C++](./C++/unique-binary-search-trees-ii.cpp) [Python](./Python/unique-binary-search-trees-ii.py) | _O(4^n / n^(3/2)_ | _O(4^n / n^(3/2)_ | Medium || 98| [Validate Binary Search Tree](https://leetcode.com/problems/validate-binary-search-tree/)|[C++](./C++/validate-binary-search-tree.cpp) [Python](./Python/validate-binary-search-tree.py)| _O(n)_ | _O(1)_ | Medium || 100| [Same Tree](https://leetcode.com/problems/same-tree/) |[C+](./C++/same-tree.cpp) [Python](./Python/same-tree.py) | _O(n)_ | _O(h)_ | Easy || 104| [Maximum Depth of Binary Tree](https://leetcode.com/problems/maximum-depth-of-binary-tree/)| [C++](./C++/maximum-depth-of-binary-tree.cpp) [Python](./Python/maximum-depth-of-binary-tree.py)| _O(n)_ | _O(h)_ | Easy || 105| [Construct Binary Tree from Preorder and Inorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/) | [C++](./C++/construct-binary-tree-from-preorder-and-inorder-traversal.cpp) [Python](./Python/construct-binary-tree-from-preorder-and-inorder-traversal.py) | _O(n)_ | _O(n)_ | Medium || 106| [Construct Binary Tree from Inorder and Postorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal/) | [C++](./C++/construct-binary-tree-from-inorder-and-postorder-traversal.cpp) [Python](./Python/construct-binary-tree-from-inorder-and-postorder-traversal.py) | _O(n)_ | _O(n)_ | Medium || 108| [Convert Sorted Array to Binary Search Tree](https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree/) | [C++](./C++/convert-sorted-array-to-binary-search-tree.cpp) [Python](./Python/convert-sorted-array-to-binary-search-tree.py) | _O(n)_ | _O(logn)_ | Medium || 109| [Convert Sorted List to Binary Search Tree](https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree/) | [C++](./C++/convert-sorted-list-to-binary-search-tree.cpp) [Python](./Python/convert-sorted-list-to-binary-search-tree.py) | _O(n)_ | _O(logn)_ | Medium || 110| [Balanced Binary Tree](https://leetcode.com/problems/balanced-binary-tree/) | [Python](./Python/balanced-binary-tree.py) | _O(n)_| _O(h)_ | Easy || 111| [Minimum Depth of Binary Tr

# Machine learning algorithms A collection of minimal and clean implementations of machine learning algorithms. ### Why? This project is targeting people who want to learn internals of ml algorithms or implement them from scratch. The code is much easier to follow than the optimized libraries and easier to play with. All algorithms are implemented in Python, using numpy, scipy and autograd. ### Implemented: * [Deep learning (MLP, CNN, RNN, LSTM)](mla/neuralnet) * [Linear regression, logistic regression](mla/linear_models.py) * [Random Forests](mla/ensemble/random_forest.py) * [Support vector machine (SVM) with kernels (Linear, Poly, RBF)](mla/svm) * [K-Means](mla/kmeans.py) * [Gaussian Mixture Model](mla/gaussian_mixture.py) * [K-nearest neighbors](mla/knn.py) * [Naive bayes](mla/naive_bayes.py) * [Principal component analysis (PCA)](mla/pca.py) * [Factorization machines](mla/fm.py) * [Restricted Boltzmann machine (RBM)](mla/rbm.py) * [t-Distributed Stochastic Neighbor Embedding (t-SNE)](mla/tsne.py) * [Gradient Boosting trees (also known as GBDT, GBRT, GBM, XGBoost)](mla/ensemble/gbm.py) * [Reinforcement learning (Deep Q learning)](mla/rl) ### Installation cd MLAlgorithms pip install scipy numpy pip install . ### How to run examples without installation cd MLAlgorithms python -m examples.linear_models ### How to run examples within Docker cd MLAlgorithms docker build -t mlalgorithms . docker run --rm -it mlalgorithms bash python -m examples.linear_models ### Contributing Your contributions are always welcome! Feel free to improve existing code, documentation or implement new algorithm. Please open an issue to propose your changes if they big are enough.

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