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Explore 75 essential problems frequently asked in tech interviews. Each solution includes detailed explanations and time/space complexity analysis. Boost your coding skills and interview preparedness!

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Blind 75 LeetCode Solutions

Blind 75 LeetCode

This repository contains a curated list of 75 LeetCode problems that are commonly known as the "Blind 75." These problems cover a wide range of data structures and algorithms and are frequently asked in technical interviews. Solving these problems can help you build a strong foundation in algorithmic problem-solving.

Problem List

Array & Hashing

Array & Hashing

Problem Name Difficulty
217. Contains Duplicate Easy
242. Valid Anagram Easy
1. Two Sum Easy
49. Group Anagrams Medium
347. Top K Frequent Elements Medium
238. Product of Array Except Self Medium
659. Encode and Decode Strings Medium
128. Longest Consecutive Sequence Hard

Two Pointers

Array & Hashing

Problem Name Difficulty
125. Valid Palindrome Easy
15. 3Sum Medium
11. Container With Most Water Medium

Sliding Window

Array & Hashing

Problem Name Difficulty
121. Best Time to Buy And Sell Stock Easy
3. Longest Substring Without Repeating Characters Medium
424. Longest Repeating Character Replacement Medium
76. Minimum Window Substring Hard

Stack

Array & Hashing

Problem Name Difficulty
20. Valid Parentheses Easy

Binary Search

Array & Hashing

Problem Name Difficulty
153. Find Minimum In Rotated Sorted Array Medium
33. Search In Rotated Sorted Array Medium

Linked List

Array & Hashing

Problem Name Difficulty
206. Reverse Linked List Easy
21. Merge Two Sorted Lists Easy
143. Reorder List Medium
19. Remove Nth Node From End of List Medium
141. Linked List Cycle Medium
23. Merge K Sorted Lists Hard

Trees

Array & Hashing

Problem Name Difficulty
226. Invert Binary Tree Easy
104. Maximum Depth of Binary Tree Easy
100. Same Tree Easy
572. Subtree of Another Tree Easy
235. Lowest Common Ancestor of a Binary Search Tree Easy
102. Binary Tree Level Order Traversal Medium
98. Validate Binary Search Tree Medium
230. Kth Smallest Element In a BST Medium
105. Construct Binary Tree From Preorder And Inorder Traversal Medium
124. Binary Tree Maximum Path Sum Hard
297. Serialize And Deserialize Binary Tree Hard

Tries

Array & Hashing

Problem Name Difficulty
208. Implement Trie Prefix Tree Medium
211. Design Add And Search Words Data Structure Medium
212. Word Search II Hard

Heap / Priority Queue

Array & Hashing

Problem Name Difficulty
295. Find Median From Data Stream Hard

Backtracking

Array & Hashing

Problem Name Difficulty
39. Combination Sum Medium
79. Word Search Medium

Graphs

Array & Hashing

Problem Name Difficulty
200. Number of Islands Medium
133. Clone Graph Medium
417. Pacific Atlantic Water Flow Medium
207. Course Schedule Medium
323. Number of Connected Components In An Undirected Graph Medium
261. Graph Valid Tree Medium

Advanced Graphs

Array & Hashing

Problem Name Difficulty
269. Alien Dictionary Hard

1-D Dynamic Programming

Array & Hashing

Problem Name Difficulty
70. Climbing Stairs Easy
198. House Robber Easy
213. House Robber II Medium
5. Longest Palindromic Substring Medium
647. Palindromic Substrings Medium
91. Decode Ways Medium
322. Coin Change Medium
152. Maximum Product Subarray Medium
139. Word Break Medium
300. Longest Increasing Subsequence Medium

2-D Dynamic Programming

Array & Hashing

Problem Name Difficulty
62. Unique Paths Medium
1143. Longest Common Subsequence Medium

Greedy

Array & Hashing

Problem Name Difficulty
53. Maximum Subarray Easy
55. Jump Game Medium

Intervals

Array & Hashing

Problem Name Difficulty
57. Insert Interval Hard
56. Merge Intervals Medium
435. Non Overlapping Intervals Medium
252. Meeting Rooms Easy
253. Meeting Rooms II Medium

Math & Geometry

Array & Hashing

Problem Name Difficulty
48. Rotate Image Medium
54. Spiral Matrix Medium
73. Set Matrix Zeroes Medium

Bit Manipulation

Array & Hashing

Problem Name Difficulty
191. Number of 1 Bits Easy
338. Counting Bits Medium
190. Reverse Bits Easy
268. Missing Number Easy
371. Sum of Two Integers Medium

How to Use

  1. Clone or download this repository to your local machine.
git clone https://github.com/mohsentabibian/LeetCode-Solutions/Blind-75-LeetCode.git
  1. Navigate to the directory of the specific problem you want to solve.
cd Blind-75-LeetCode/Problem-Directory
  1. Open the problem's directory to find its description, code template, and solution(s).

  2. Solve the problem using your preferred programming language.

  3. Check the solution(s) provided in the directory for reference and to compare your solution.

Contribute

If you have a better solution or want to add more problems to the collection, feel free to contribute. You can create a pull request or open an issue to discuss additions or improvements.

Resources

  • LeetCode: The official LeetCode website.
  • LeetCode Discuss: LeetCode's discussion forum for each problem. You can find helpful hints and discussions here.

Disclaimer

This repository is meant for educational purposes and to help individuals prepare for technical interviews. Please respect LeetCode's terms of use and guidelines when using this repository.

Code of Conduct

We have a Code of Conduct that we expect all contributors to adhere to. By participating in this project, you agree to follow this code.

Security Policy

We take security seriously. Please review our Security Policy for information on reporting security vulnerabilities.

Happy coding!

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Explore 75 essential problems frequently asked in tech interviews. Each solution includes detailed explanations and time/space complexity analysis. Boost your coding skills and interview preparedness!

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