📝 Update README.md

README.md

@@ -7,6 +7,71 @@ Solutions to [LeetCode](https://leetcode.com/) problems written in Swift.
 [![MIT License][license-shield]][license-url]
 [![LinkedIn][linkedin-shield]][linkedin-url]
 
+## Requirements
+
+* Xcode 15+
+* Swift 5.9
+
+## Running the solutions
+
+Each problem solution has a test case in the [`Tests`][test-cases-folder-url] folder.
+
+You can modify the test cases, provide new inputs and expected outputs.
+
+Or you can run the companion app `LeetSwift`, to browse and run the test cases of the solutions for the problems you would like to check.
+
+## Project structure
+Here's the representation of the project structure, to make it easier to navigate through all folders.  
+
+Please pay attention to this if adding problems and implementing solutions, so everything conforms to this folder structure.
+``` bash
+.
+├── LICENSE
+├── LeetSwift                                # Companion app
+│   ├── Package.swift                        # Dummy package - excludes this folder from the main package
+│   └── ...                                  # Companion app project files
+├── LeetSwift.xcworkspace                    # Workspace
+├── Package.swift                            # Main package
+├── Sources                                  # Main package source code
+│   └── LeetSwiftCore                        # Library folder
+│       ├── Problems                         # Descriptions and definitions
+│       │   └── XXX - Problem title          # Problem files
+│       │       └── ProblemDefinition.swift  # Protocol-based problem definition
+│       └── Solutions                        # Implementation of solutions
+│           └── XXX - Problem title          # Problem solution folder
+│               └── ProblemSolution.swift    # A solution to the corresponding problem
+└── Tests                                    # Main package source code tests
+    └── LeetSwiftCoreTests                   # Core tests
+        ├── Core                             # Core testing support files
+        │   ├── TestCaseProviding.swift      # Testing support
+        │   └── TestData.swift               # Definition of test data
+        └── Problems                         # Tests for the solutions of all problems
+            └── XXX - Problem title          # Problem solution test folder
+                └── ProblemTests.swift       # Run test cases for a solution to the corresponding problem
+```
+
+### Companion App (🚧 Under construction 👷)
+The companion app `LeetSwift` is intended to make it easier to browse and run the solutions. You can run it on any platform.
+
+### Problems
+
+Below there is a table with all the problems with their corresponding solution.
+
+You can find the walkthrough with detailed solution of all the problems on my blog [jobear.dev][jobear-blog-url], or concrete problem solution walkthrough on the `Walkthrough` column (🚧 Under construction 👷).
+
+| # | Title | Solution | Difficulty | Topics | Time | Space | Walkthrough |
+| --- | --- | --- | --- | --- | --- | --- | --- |
+| 1 | [Two Sum][001-problem] | [Solution][001-solution] | ![Difficulty][difficulty-easy-shield] | **`A`** **`HT`** | | | |
+
+#### Topics
+- **`A`** : Array
+- **`HT`** : Hash Table
+
+## Approach
+Here, I use the TDD approach, writing the test cases before writing the solution. This way, I can quickly verify if the solution works as expected. The goals is to always have test cases for all the problems and to make all of them green.
+
+If you would like to contribute, I recomment to write your solutions using this same approach.
+
 <!-- Markdown references https://www.markdownguide.org/basic-syntax/#reference-style-links -->
 [last-commit-shield]: https://img.shields.io/github/last-commit/jobearrr/LeetSwift?style=flat
 [last-commit-url]: https://github.com/jobearrr/LeetSwift/commits/master
@@ -15,4 +80,12 @@ Solutions to [LeetCode](https://leetcode.com/) problems written in Swift.
 [license-shield]: https://img.shields.io/github/license/jobearrr/LeetSwift.svg?style=flat
 [license-url]: https://github.com/jobearrr/LeetSwift/LICENSE
 [linkedin-shield]: https://img.shields.io/badge/-LinkedIn-black.svg??style=flat&logo=linkedin&colorB=555
-[linkedin-url]: https://www.linkedin.com/in/jobertsa/
+[linkedin-url]: https://www.linkedin.com/in/jobertsa
+[jobear-blog-url]: https://jobear.dev
+[test-cases-folder-url]: https://github.com/jobearrr/LeetSwift/tree/main/Tests/LeetSwiftCoreTests/Problems
+[difficulty-easy-shield]: https://img.shields.io/badge/%20Difficulty-Easy-brightgreen.svg
+[difficulty-medium-shield]: https://img.shields.io/badge/%20Difficulty-Medium-orange.svg
+[difficulty-hard-shield]: https://img.shields.io/badge/%20Difficulty-Hard-red.svg
+[001-problem]: https://leetcode.com/problems/two-sum
+[001-solution]: https://github.com/jobearrr/LeetSwift/blob/main/Sources/LeetSwiftCore/Solutions/001%20-%20Two%20Sum/TwoSumSolution.swift
+