🧮 LeetSwift

Solutions to LeetCode problems written in Swift.

Requirements

• Xcode 15.2+
• Swift 5.9

Running the solutions

Each solution has test cases that can be found in the SolutionsTests folder.
I try to write tests covering as much of the code as possible (on top of the test cases provided by LeetCode).
You can modify the test cases, and provide new inputs and expected outputs.

Project structure

Here's the representation of the project structure, to make it easier to navigate through all the content.

Please pay attention to this if adding problems and implementing solutions, so everything conforms to this folder structure.

.
├── LeetSwift                                      # Companion app
│   └── ...                                        # Project files
├── LeetSwift.xcworkspace
├── Package.swift                                  # LeetSwift package spec
├── Sources
│   ├── Core                                       # Data structures, helpers, etc.
│   │   └── ...
│   ├── Solutions
│   │   ├── ...
│   │   └── XXX - Problem title
│   │       ├── ProblemXXXDefinition.swift         # Problem definition
│   │       ├── ProblemXXX<M>Solution.swift        # Solution M
│   │       ├── ProblemXXX<N>Solution.swift        # Solution N
│   │       ├── ...                                # Other solutions
│   │       └── README.md                          # Documentation and solutions
│   └── TestSupport                                # Supporting classes / extensions
│       ├── Array+ListNode.swift
│       ├── TestCaseProviding.swift
│       └── TestData.swift
└── Tests
    ├── CoreTests
    │   └── ...
    ├── SolutionsTests
    │   ├── ProblemXXXTests.swift                  # Test all solutions for Problem XXX
    │   └── ...                                    # Other tests
    └── TestSupportTests
        └── Utils
            └── ...                                # Test support classes

Problems

Below, you can find a table with all the problems with their corresponding solution. You can find a detailed walkthrough of the solutions to these problems on my blog jobear.dev.

#	Problem & Solutions	Topics	Difficulty
1	Two Sum	A HT
2	Add Two Numbers	LL M R
3	Longest Substring Without Repeating Characters	HT S SW
4	Median of Two Sorted Arrays	A BS DC
5	Longest Palindromic Substring	TP S DP
6	Zigzag Conversion	S
7	Reverse Integer	M
8	String to Integer (atoi)	S
9	Palindrome Number	M
10	Regular Expression Matching	S DP R
11	Container With Most Water	A TP G
12	Integer to Roman	HT M S
13	Roman to Integer	HT M S
14	Longest Common Prefix	S T
15	3Sum	A TP SO
16	3Sum Closest	A TP SO
17	Letter Combinations of a Phone Number	HT S BT
18	4Sum	A TP SO
19	Remove Nth Node From End of List	LL TP
20	Valid Parentheses	S ST
21	Merge Two Sorted Lists	LL R
22	Generate Parentheses	S DP BT
23	Merge k Sorted Lists	LL DC H MS
24	Swap Nodes in Pairs	LL R
25	Reverse Nodes in k-Group	LL R
26	Remove Duplicates from Sorted Array	A TP
27	Remove Element	A TP
28	Find the Index of the First Occurrence in a String	TP S SM
29	Divide Two Integers	B BM
30	Substring with Concatenation of All Words	HT S SW
31	Next Permutation	A TP
32	Longest Valid Parentheses	S DP ST
33	Search in Rotated Sorted Array
34	Find First and Last Position of Element in Sorted Array
35	Search Insert Position
36	Valid Sudoku
37	Sudoku Solver
38	Count and Say
39	Combination Sum
40	Combination Sum II
41	First Missing Positive
42	Trapping Rain Water
43	Multiply Strings
44	Wildcard Matching
45	Jump Game II
46	Permutations
47	Permutations II
48	Rotate Image
49	Group Anagrams
50	Pow(x, n)
51	N-Queens
52	N-Queens II
53	Maximum Subarray
54	Spiral Matrix
55	Jump Game
56	Merge Intervals
57	Insert Interval
58	Length of Last Word
59	Spiral Matrix II
60	Permutation Sequence
61	Rotate List
62	Unique Paths
63	Unique Paths II
64	Minimum Path Sum
65	Valid Number
66	Plus One
67	Add Binary
68	Text Justification
69	Sqrt(x)
70	Climbing Stairs
71	Simplify Path
72	Edit Distance
73	Set Matrix Zeroes
74	Search a 2D Matrix
75	Sort Colors
76	Minimum Window Substring
77	Combinations
78	Subsets
79	Word Search
80	Remove Duplicates from Sorted Array II
81	Search in Rotated Sorted Array II
82	Remove Duplicates from Sorted List II
83	Remove Duplicates from Sorted List
84	Largest Rectangle in Histogram
85	Maximal Rectangle
86	Partition List
87	Scramble String
88	Merge Sorted Array
89	Gray Code
90	Subsets II
91	Decode Ways
92	Reverse Linked List II
93	Restore IP Addresses
94	Binary Tree Inorder Traversal
95	Unique Binary Search Trees II
96	Unique Binary Search Trees
97	Interleaving String
98	Validate Binary Search Tree
99	Recover Binary Search Tree
100	Same Tree

Topics

• A : Array
• HT : Hash Table
• LL: Linked List
• M: Math
• R: Recursion
• S: String
• SW: Sliding Window
• BS: Binary Search
• DC: Divide and Conquer
• TP: Two Pointers
• DP: Dynamic Programming
• G: Greedy
• T: Trie
• SO: Sorting
• BT: Backtracking
• ST: Stack
• H: Heap
• MS: Merge Sort
• SM: String Matching
• BM: Bit Manipulation

TDD 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 goal is always to have enough test cases for all the problems and then work on the solution until all of these test cases are green.

If you would like to contribute, please use this same approach.

License

Please note this project uses the GNU AGPLv3 license, which requires any code or software that uses it to make their code completely available.

This project is intended to be used for educational purposes only.

Please acknowledge the license and contact me if you intend to use any content from here.