Leetcode 30-Day Challenge April and May Edition

Summary

• This project aims at solving LeetCode 30-Day Challenge April Edition and May LeetCoding Challenge problems.
• We provide straightforward solutions. All solutions and tests are written in Swift.
• There are 30 programming problems and solutions for April challenge.
• An additional set of 30 code problems and solutions will be uploaded by the end of May LeetCoding Challenge.

Articles for April Edition

• iOS Interview Prep Guide: 30-Day Code Challenge in Swift — Week 1/5
• iOS Interview Prep Guide: 30-Day Code Challenge in Swift — Week 2/5
• iOS Interview Prep Guide: 30-Day Code Challenge in Swift — Week 3/5
• iOS Interview Prep Guide: 30-Day Code Challenge in Swift — Week 4/5
• iOS Interview Prep Guide: 30-Day Code Challenge in Swift — Week 5/5

Articles for May Edition

Updating in progress

• Top 15 Swift Code Interview Questions from May Code Challenge — Part 1/3

Difficulty Legends

Difficulty	Easy	Medium	Hard
Icon	📗	📙	📕

April Challenge

April 1st - April 30th

Day	Diffculty	Problem	Solution
1	📗	Single Number	Solution
2	📗	Happy Number	Solution
3	📗	Maximum Subarray	Solution
4	📗	Move Zeroes	Solution
5	📗	Best Time to Buy and Sell Stock II	Solution
6	📙	Group Anagrams	Solution
7	📗	Counting Elements	Solution
8	📗	Middle of the Linked List	Solution
9	📗	Backspace String Compare	Solution
10	📗	Min Stack	Solution
11	📗	Diameter of Binary Tree	Solution
12	📗	Last Stone Weight	Solution
13	📙	Contiguous Array	Solution
14	📗	Perform String Shifts	Solution
15	📙	Product of Array Except Self	Solution
16	📙	Valid Parenthesis String	Solution
17	📙	Number of Islands	Solution
18	📙	Minimum Path Sum	Solution
19	📙	Search in Rotated Sorted Array	Solution
20	📙	Construct Binary Search Tree from Preorder Traversal	Solution
21	📙	Leftmost Column with at Least a One	Solution
22	📙	Subarray Sum Equals K	Solution
23	📙	Bitwise AND of Numbers Range	Solution
24	📙	LRU Cache	Solution
25	📙	Jump Game	Solution
26	📙	Longest Common Subsequence	Solution
27	📙	Maximal Square	Solution
28	📙	First Unique Number	Solution
29	📕	Binary Tree Maximum Path Sum	Solution
30	📙	A String Is a Root-to-Leaf Path in a Binary Tree	Solution

May Challenge

May 1st - May 31st

Day	Diffculty	Problem	Solution
1	📗	First Bad Version	Solution
2	📗	Jewels and Stones	Solution
3	📗	Ransom Note	Solution
4	📗	Number Complement	Solution
5	📗	First Unique Character in a String	Solution
6	📗	Majority Element	Solution
7	📗	Cousins in Binary Tree	Solution
8	📗	Check If It Is a Straight Line	Solution
9	📗	Valid Perfect Square	Solution
10	📗	Find the Town Judge	Solution
11	📗	Flood Fill	Solution
12	📙	Single Element in a Sorted Array	Solution
13	📙	Remove K Digits	Solution
14	📙	Implement Trie (Prefix Tree)	Solution
15	📙	Maximum Sum Circular Subarray	Solution
16	📙	Odd Even Linked List	Solution
17	📙	Find All Anagrams in a String	Solution
18	📙	Permutation in String	Solution
19	📙	Online Stock Span	Solution
20	📙	Kth Smallest Element in a BST	Solution
21	📙	Count Square Submatrices with All Ones	Solution
22	📙	Sort Characters By Frequency	Solution
23	📙	Interval List Intersections	Solution
24	📙	Construct Binary Search Tree from Preorder Traversal	Solution
25	📙	Uncrossed Lines	Solution
26	📙	Contiguous Array	Solution
27	📙	Possible Bipartition	Solution
28	📙	Counting Bits	Solution
29	📙	Course Schedule	Solution
30	📙	K Closest Points to Origin	Solution
31	📕	Edit Distance	Solution