73 - The best number 🤓

According to Sheldon Cooper the best number is 73, because 73 is the 21st prime number. Its mirror, 37, is the 12th prime number. 21 is the product of multiplying 7 by 3 and in binary, 73 is a palindrome: 1001001

Sheldon Cooper (character in the famous series "The Big-Bang Theory")

What is this? 🚀

This is a repository that will take you by the hand in the 73 most useful LeetCode problems, well they are actually 76, 😬 the algorithms are written in C, C++ and C#, I wrote each program in the most optimal way and included the main function or method of the program to test on your machine, a README file with solution notes and for problems 252, 253, 269, 271 and 323 being Premium subscription problems, I included a README with the description of each problem. 🤓

No hurry, but no rest

Repository structure 📦

The repository is divided into 4 folders:

|- Repository
    |- .vscode
        |- tasks.json
    |- Problems
        |- Arrays
        |- Matrix
            |- Rotate-Image
                |- Rotate-Image.c
                |- Rotate-Image.cpp
                |- Rotate-Image.cs
                |- Rotate-Image.csproj
                |- README.md
            |- Set-Matrix-Zeroes
            |- Spiral-Matrix
            |- Word-Search
        |- Strings
        |- Intervals
        |- Binary Search
        |- Dynamic Programming
        |- Linked Lists
        |- Trees
        |- Heaps
        |- Graphs
    |- Sources
        |- Sheldon.gif

• .vscode: Contains the 'tasks.json' file that configures the build task in Visual Studio Code for /usr/bin/g++ and the configuration for the output generated ${fileDirname}\\${fileBasenameNoExtension}.out

• Problems: Contains the folders for each topic, inside it has a folder per problem and inside each folder is the source code and the README that explains the problem, for example the Two-Sum folder contains the C source code Two-Sum.c (Only in the first problem of each topic there is an implementation in C language to go a little deeper), the C++ source code Two-Sum .cpp, the C# source code in Two-Sum.cs and the .NET project settings in Two-Sum.csproj and finally the README.md file

• Sources: Contains the images and gifs used in the repository, such as Sheldon Cooper's 😁 gif

Configuration🔧

The focus of this repository is towards C#, so you can use it from Windows, Linux, Mac, Docker or even GitHub Codespaces, but it is intended to be used on Linux, specifically an Ubuntu based distribution or Red Hat based distribution, no matter if it is a complete distro or a WSL distro. All solutions are also written in C++, only the first problem of each topic includes the solution in C and only in the last problem of each topic includes the solution in F#, so to use this repository you must have installed:

To compile C# and F# you need to install dotnet-sdk

• dotnet-sdk-8.0

At this time the dotnet sdk is available from the Ubuntu 22.04 and Fedora 39 source, so, to install you can copy and paste the following commands:

Ubuntu 22.04 or later:

sudo apt update && \
    sudo apt install -y dotnet-sdk-8.0

Fedora 39 or later:

sudo dnf install dotnet-sdk-8.0

Note: To install on other linux versions or linux distributions, please check this page.

If you want use this repository with C and C++ then you should install gcc and g++

• gcc
• g++

To install them on Debian based distributions you can type:

Debian based distributions:

sudo apt update && \
    sudo apt install build-essential -y

Red hat based distributions:

sudo dnf install gcc g++ -y

Index 📖

Arrays

#	Title	Solution	Difficulty
0001	Two Sum	C - C++ - C#	Easy
0011	Container With Most Water	C++ - C#	Medium
0015	3Sum	C++ - C#	Medium
0033	Search in Rotated Sorted Array	C++ - C#	Medium
0053	Maximum Subarray	C++ - C#	Medium
0121	Best Time to Buy and Sell Stock	C++ - C#	Medium
0152	Maximum Product Subarray	C++ - C#	Medium
0153	Find Minimum in Rotated Sorted Array	C++ - C#	Medium
0217	Contains Duplicate	C++ - C#	Easy
0238	Product of Array Except Self	C++ - C# - F#	Easy

Matrix

#	Title	Solution	Difficulty
0048	Rotate Image	C - C++ - C#	Medium
0054	Spiral Matrix	C++ - C#	Medium
0073	Set Matrix Zeroes	C++ - C#	Medium
0079	Word Search	C++ - C# - F#	Medium

Strings

#	Title	Solution	Difficulty
0003	Longest Substring Without Repeating Characters	C - C++ - C#	Medium
0005	Longest Palindromic Substring	C++ - C#	Medium
0020	Valid Parentheses	C++ - C#	Easy
0049	Group Anagrams	C++ - C#	Medium
0076	Minimum Window Substring	C++ - C#	Hard
0125	Valid Palindrome	C++ - C#	Easy
0242	Valid Anagram	C++ - C#	Easy
0271	Encode and Decode Strings	C++ - C#	Medium
0424	Longest Repeating Character Replacement	C++ - C#	Medium
0647	Palindromic Substrings	C++ - C# - F#	Medium

Intervals

#	Title	Solution	Difficulty
0056	Merge Intervals	C - C++ - C#	Medium
0057	Insert Interval	C++ - C#	Medium
0252	Meeting Rooms	C++ - C#	Easy
0253	Meeting Rooms II	C++ - C#	Medium
0435	Non-overlapping Intervals	C++ - C# - F#	Medium

Binary

#	Title	Solution	Difficulty
0190	Reverse Bits	C - C++ - C#	Easy
0191	Number of 1 Bits	C++ - C#	Easy
0268	Missing Number	C++ - C#	Easy
0338	Counting Bits	C++ - C#	Easy
0371	Sum of Two Integers	C++ - C# - F#	Medium

Dynamic Programming

#	Title	Solution	Difficulty
0055	Jump Game	C - C++ - C#	Medium
0062	Unique Paths	C++ - C#	Medium
0070	Climbing Stairs	C++ - C#	Easy
0091	Decode Ways	C++ - C#	Medium
0139	Word Break	C++ - C#	Medium
0198	House Robber	C++ - C#	Medium
0213	House Robber II	C++ - C#	Medium
0300	Longest Increasing Subsequence	C++ - C#	Medium
0322	Coin Change	C++ - C#	Medium
0377	Combination Sum IV	C++ - C#	Medium
1143	Longest Common Subsequence	C++ - C# - F#	Medium

Linked Lists

#	Title	Solution	Difficulty
0019	Remove Nth Node From End of List	C - C++ - C#	Medium
0021	Merge Two Sorted Lists	C++ - C#	Easy
0023	Merge k Sorted Lists	C++ - C#	Hard
0141	Linked List Cycle	C++ - C#	Easy
0143	Reorder List	C++ - C#	Medium
0206	Reverse Linked List	C++ - C# - F#	Easy

Trees

#	Title	Solution	Difficulty
0098	Validate Binary Search Tree	C - C++ - C#	Medium
0100	Same Tree	C++ - C#	Easy
0102	Binary Tree Level Order Traversal	C++ - C#	Medium
0104	Maximum Depth of Binary Tree	C++ - C#	Easy
0105	Construct Binary Tree from Preorder and Inorder Traversal	C++ - C#	Medium
0124	Binary Tree Maximum Path Sum	C++ - C#	Hard
0208	Implement Trie (Prefix Tree)	C++ - C#	Medium
0211	Design Add and Search Words Data Structure	C++ - C#	Medium
0212	Word Search II	C++ - C#	Hard
0226	Invert Binary Tree	C++ - C#	Hard
0230	Kth Smallest Element in a BST	C++ - C#	Medium
0235	Lowest Common Ancestor of a Binary Search Tree	C++ - C#	Medium
0297	Serialize and Deserialize Binary Tree	C++ - C#	Hard
0572	Subtree of Another Tree	C++ - C# - F#	Easy

Heaps

#	Title	Solution	Difficulty
0295	Find Mediumn from Data Stream	C - C++ - C#	Hard
0347	Top K Frequent Elements	C++ - C#	Medium
0355	Design Twitter	C++ - C# - F#	Medium

Graphs

#	Title	Solution	Difficulty
0128	Longest Consecutive Sequence	C - C++ - C#	Medium
0133	Clone Graph	C++ - C#	Medium
0200	Number of Islands	C++ - C#	Medium
0207	Course Schedule	C++ - C#	Medium
0261	Graph Valid Tree	C++ - C#	Medium
0269	Alien Dictionary	C++ - C#	Hard
0323	Number of Connected Components in an Undirected Graph	C++ - C#	Medium
0417	Pacific Atlantic Water Flow	C++ - C# - F#	Medium

Build with 🛠️

• C
• C++
• C#
• F#
• Ubuntu
• VS Code

C# Conferences 📊

• High Speed History of C#
• Mono Edge - Miguel de Icaza
• .NET at Stack Overflow | .NET Conf 2022
• Miguel de Icaza's Vision Keynote - UnoConf 2019
• Full stack web UI with Blazor in .NET 8 | .NET Conf 2023
• Patterns for high-performance C# - Federico Andres Lois
• Let's design a new C# language feature! | .NET Conf 2022
• Adam SITNIK: Solving .NET performance issues | UCP2019
• What’s Next in C#? - Mads Torgersen - Copenhagen DevFest 2023
• S101 - Keynote with Scott Hunter, Mads Torgersen, and Miguel De Icaza
• The functional journey of C# - Mads Torgersen - NDC Copenhagen 2022
• Stop using Entity Framework as a DTO provider! - Chris Klug - NDC Oslo 2023
• You are doing logging in .NET wrong. Let’s fix it. - Nick Chapsas - NDC Oslo 2023
• .NET Systems Programming Learned the Hard Way - Aaron Stannard - NDC Oslo 2023
• Keynote: The Microsoft Open Source Cinematic Universe - Phase 2 - Scott Hanselman
• Using C# Source Generators to Build a .NET IoT Device - Alon Fliess - NDC Melbourne 2022
• Patterns for application development with ASP.NET Core - Damian Edwards & David Fowler
• Performance tricks I learned from contributing to open source .NET packages - Daniel Marbach
• Real-world examples on optimizing .NET performance - Stefán Jökull Sigurðarson - NDC Oslo 2023

C++ Conferences 📊

• Pontus Nyman: C++ in Space
• Bjarne Stroustrup - The Essence of C++
• CppCon 2015: Kate Gregory “Stop Teaching C"
• Bjarne Stroustrup: C++ | Lex Fridman Podcast #48
• Bjarne Stroustrup: Why you should avoid Linked Lists
• Keynote: C++'s Superpower - Matt Godbolt - CPPP 2021
• CppCon 2016: Jason Turner “Practical Performance Practices"
• Can C++ be 10x Simpler & Safer? - Herb Sutter - CppCon 2022
• C++ in Constrained Environments - Bjarne Stroustrup - CppCon 2022
• Keynote: "Am I A Good Programmer?" - Kate Gregory - CppNorth 2022
• CppCon 2017: Bjarne Stroustrup “Learning and Teaching Modern C++”
• CppCon 2017: Peter Goldsborough “A Tour of Deep Learning With C++”
• CppCon 2017: Louis Brandy “Curiously Recurring C++ Bugs at Facebook”
• CppCon 2018: Peter Goldsborough “Machine Learning in C++ with PyTorch”
• CppCon 2014: Herb Sutter "Back to the Basics! Essentials of Modern C++ Style"
• CppCon 2016: Bjarne Stroustrup "The Evolution of C++ Past, Present and Future"
• The Most Important Optimizations to Apply in Your C++ Programs - Jan Bielak - CppCon 2022
• Trading at light speed: designing low latency systems in C++ - David Gross - Meeting C++ 2022
• CppCon 2018: Gordon Brown “A Modern C++ Programming Model for GPUs using Khronos SYCL”
• The Imperatives Must Go! [Functional Programming in Modern C++] - Victor Ciura - CppCon 2022
• Bjarne Stroustrup's Closing Keynote at Code Europe 2022 in Cracow – "How to evolve a language"
• Writing Safety Critical Automotive Software for High Perf AI Hardware - Michael Wong - CppCon 2019

References 📚

Cppreference.com. (s. f.). https://en.cppreference.com/w/

Eckel, B. (2004). Thinking in C++. Thinking in C++ (2nd ed.). Pearson.

C# Docs - Get started, Tutorials, reference. https://learn.microsoft.com/en-us/dotnet/csharp/

Cormen, T. H., Leiserson, C. E., Rivest, R. L. & Stein, C. (2009). Introduction to Algorithms (3rd ed.). MIT Press.

Acknowledgments 🎁

Written with ❤️ by Jonas Lara for anyone who is interested