Leetcode Solutions

This repository contains my solutions (mostly written in Python) to the sets of problems from https://leetcode.com. I try to approach each question as if it were a interview question and attempt to simulate an actual interview by asking clarifying questions when possible. Some of the Medium/Hard problems or complicated algorithms have detailed explanations in order to clarify the methods used.
If you have a more efficient method, please let me know! I'm always eager to learn how to optimize these algorithms!
Email me at: juliusfan98@gmail.com

CSES

This folder contains solutions in Python to the questions from the CSES problem set.

Cracking the Coding Interview Answers

This folder contains answers to the problems in Cracking the Coding Interview by Gayle Laakman Mcdowell. These answers are written in Python alone. Test cases have been adapted from various online sources.

Other Useful Resources

This is but one of my many practice resources that I've used for my interview preparation. Others include

• Udacity
• Philip Guo's Interview Tips
• Coding Interview University
• Free Code Camp's Master the Coding Interview Video
• Medium's List of Important Algorithms
• Cracking the Coding Interview, 4th Edition

Solutions

#	Title	Solution	Difficulty	Explanation
0001	Two Sum	Python	Easy
0002	Add Two Numbers	Python	Medium
0003	Longest Substring Without Repeating Characters	Python	Medium	Sliding Window
0004	Median of Two Sorted Arrays	Python	Hard	Binary Search
0005	Longest Palindrome Substring	Python	Medium	Manacher's Algorithm
0006	ZigZag Conversion	Python	Medium
0007	Reverse Integer	Python	Easy
0008	String to Number (atoi)	Python	Easy
0009	Palindrome Number	Python	Easy
0011	Container With Most Water	Python	Medium
0012	Integer to Roman	Python	Easy
0013	Roman to Integer	Python	Easy
0014	Longest Common Prefix	Python	Easy
0016	3Sum Closest	Python	Medium
0017	Letter Combinations of a Phone Number	Python	Medium
0019	Remove Nth Node from End of List	Python	Medium
0020	Valid Parenthesis	Python	Easy
0021	Merge Two Sorted Lists	Python	Easy
0023	Merge K Sorted Lists	Python	Hard
0022	Generate Parenthesis	Python	Medium
0026	Remove Duplicates From Sorted Array	Python	Easy
0027	Remove Element	Python	Easy
0028	Implement StrStr()	Python	Easy	KMP Explanation
0033	Search in Rotated Sorted Array	Python	Medium
0034	Find First and Last Position of Element in Sorted Array	Python	Medium
0035	Search Insert Position	Python	Easy
0048	Rotate Image	Python	Medium
0049	Group Anagrams	Python	Medium
0053	Maximum Subarray	Python	Easy
0055	Jump Game	Python	Medium
0070	Climbing Stairs	Python	Easy
0076	Minimum Window Substring	Python	Hard	Counter + Sliding Window
0092	Reverse Linked List II	Python	Medium
0102	Binary Tree Level Order Traversal	Python	Medium
0103	Binary Tree Zigzag Level Order Traversal	Python	Medium
0107	Binary Tree Level Order Traversal II	Python	Easy
0111	Minimum Depth of Binary Tree	Python	Easy
0113	Path Sum II	Python	Medium
0116	Populating Next Right Pointers in Each Node	Python	Medium
0121	Best Time to Buy and Sell Stock	Python	Easy
0122	Best Time to Buy and Sell Stock II	Python	Easy
0124	Binary Tree Maximum Path Sum	Python	Hard
0136	Single Number	Python	Easy
0141	Linked List Cycle	Python	Easy	Set or Tortoise and Hare
0152	Maximum Product Subarray	Python	Medium
0153	Find Minimum in Rotated Sorted Array	Python	Medium
0155	Min Stack	Python	Easy
0198	House Robbers	Python	Easy	Dynamic Programming
0200	Num Islands	Python	Medium
0202	Happy Number	Python	Easy
0206	Reverse Linked List	Python	Easy
0207	Course Schedule	Python	Medium
0208	Implement Trie (Prefix Tree)	Python	Medium
0217	Contains Duplicate	Python	Easy
0230	Kth Smallest Element in BST	Python	Medium
0235	Lowest Common Ancestor of a Binary Search Tree	Python	Easy
0238	Product of Array Except Self	Python	Medium
0242	Valid Anagram	Python	Easy
0283	Move Zeroes	Python	Easy
0295	Find Median in Data Stream	Python	Hard
0297	Serialize and Deserialize Binary Tree	Python	Hard
0322	Coin Change	Python	Medium
0328	Odd Even Linked List	Python	Medium
0347	Top K Frequent Elements	Python	Medium
0380	Insert Delete GetRandom	Python	Medium
0417	Pacific Atlantic Water Flow	Python	Medium	DFS
0424	Longest Repeating Character Replacement	Python	Medium	Sliding Window
0442	Find All Duplicates in an Array	Python	Medium
0448	Find All Numbers Disappeared in an Array	Python	Easy
0435	Non Overlapping Intervals	Python	Medium	Greedy Algorithm
0452	Minimum Number of Arrows to Burst Balloons	Python	Medium	Greedy Algorithm
0543	Diameter of Binary Tree	Python	Easy
0637	Average of Levels in Binary Tree	Python	Easy
0844	Backspace String Compare	Python	Easy
0876	Middle of the Linked List	Python	Easy
0904	Fruits Into Baskets	Python	Medium
0938	Range Sum of BST	Python	Easy
0986	Interval List Intersections	Python	Medium
1046	Last Stone Weight	Python	Easy