🧩 LeetCode Blind 75 Problem Solving

A collection of LeetCode Blind 75 solutions organized by topic.

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📊 Progress

Category	Completed	Total
Arrays / Strings	7	15
Two Pointers	1	1
HashMap / Sliding Window	0	10
Stack / Queue	1	8
Linked List	0	8
Trees	0	12
Recursion / Backtracking	1	8
Basic DP	0	10
Binary Search	1	2
Graphs	0	2
Total	11	76

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🟩 Arrays / Strings

#	Problem	Difficulty	Status
1	Two Sum	Easy	✅
3	Longest Substring Without Repeating Characters	Medium	✅
5	Longest Palindromic Substring	Medium	✅
49	Group Anagrams	Medium	✅
56	Merge Intervals	Medium	✅
125	Valid Palindrome	Easy	✅
169	Majority Element	Easy	✅
189	Rotate Array	Medium	⬜
217	Contains Duplicate	Easy	✅
238	Product of Array Except Self	Medium	⬜
242	Valid Anagram	Easy	⬜
283	Move Zeroes	Easy	⬜
438	Find All Anagrams in a String	Medium	✅

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� Two Pointers

#	Problem	Difficulty	Status
11	Container With Most Water	Medium	✅

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�🟦 HashMap / Sliding Window

#	Problem	Difficulty	Status
202	Happy Number	Easy	✅
205	Isomorphic Strings	Easy	✅
290	Word Pattern	Easy	⬜
347	Top K Frequent Elements	Medium	⬜
350	Intersection of Two Arrays II	Easy	⬜
383	Ransom Note	Easy	⬜
387	First Unique Character in a String	Easy	⬜
424	Longest Repeating Character Replacement	Medium	⬜
560	Subarray Sum Equals K	Medium	⬜
76	Minimum Window Substring	Hard	⬜

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🟨 Stack / Queue

#	Problem	Difficulty	Status
20	Valid Parentheses	Easy	✅
150	Evaluate Reverse Polish Notation	Medium	⬜
155	Min Stack	Medium	⬜
232	Implement Queue using Stacks	Easy	⬜
239	Sliding Window Maximum	Hard	⬜
394	Decode String	Medium	⬜
496	Next Greater Element I	Easy	⬜
739	Daily Temperatures	Medium	⬜

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🟧 Linked List

#	Problem	Difficulty	Status
2	Add Two Numbers	Medium	⬜
19	Remove Nth Node From End of List	Medium	⬜
21	Merge Two Sorted Lists	Easy	🚧
141	Linked List Cycle	Easy	⬜
143	Reorder List	Medium	⬜
160	Intersection of Two Linked Lists	Easy	⬜
206	Reverse Linked List	Easy	⬜
234	Palindrome Linked List	Easy	⬜

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🌳 Trees

#	Problem	Difficulty	Status
98	Validate Binary Search Tree	Medium	⬜
100	Same Tree	Easy	⬜
102	Binary Tree Level Order Traversal	Medium	⬜
104	Maximum Depth of Binary Tree	Easy	⬜
105	Construct Binary Tree from Preorder and Inorder Traversal	Medium	⬜
110	Balanced Binary Tree	Easy	⬜
112	Path Sum	Easy	⬜
226	Invert Binary Tree	Easy	⬜
230	Kth Smallest Element in a BST	Medium	⬜
235	Lowest Common Ancestor of a Binary Search Tree	Medium	⬜
297	Serialize and Deserialize Binary Tree	Hard	⬜
543	Diameter of Binary Tree	Easy	⬜

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🔁 Recursion / Backtracking

#	Problem	Difficulty	Status
17	Letter Combinations of a Phone Number	Medium	⬜
22	Generate Parentheses	Medium	⬜
39	Combination Sum	Medium	✅
46	Permutations	Medium	⬜
51	N-Queens	Hard	⬜
78	Subsets	Medium	⬜
79	Word Search	Medium	⬜
131	Palindrome Partitioning	Medium	⬜

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📈 Basic DP

#	Problem	Difficulty	Status
53	Maximum Subarray	Medium	⬜
62	Unique Paths	Medium	⬜
64	Minimum Path Sum	Medium	⬜
70	Climbing Stairs	Easy	⬜
72	Edit Distance	Medium	⬜
91	Decode Ways	Medium	⬜
121	Best Time to Buy and Sell Stock	Easy	⬜
198	House Robber	Medium	⬜
300	Longest Increasing Subsequence	Medium	⬜
322	Coin Change	Medium	⬜
416	Partition Equal Subset Sum	Medium	⬜
1143	Longest Common Subsequence	Medium	⬜

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� Binary Search

#	Problem	Difficulty	Status
33	Search in Rotated Sorted Array	Medium	✅
153	Find Minimum in Rotated Sorted Array	Medium	⬜

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🗺️ Graphs

#	Problem	Difficulty	Status
133	Clone Graph	Medium	⬜
200	Number of Islands	Medium	⬜

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�🛠️ Tech Stack

• C# (.NET 8.0)
• Java
• xUnit (Testing)

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📁 Project Structure

├── Basics/          # Java fundamentals
├── Models/          # Shared data structures (ListNode, etc.)
├── Problem Solving/ # C# solutions
└── Test/            # Unit tests

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🚀 Getting Started

# Build the project
dotnet build

# Run tests
dotnet test

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📌 Legend

Symbol	Meaning
✅	Completed
🚧	In Progress
⬜	Not Started