NeetCode & LeetCode Solutions

A well-organized collection of solutions for NeetCode 150 and LeetCode problems covering all major Data Structures & Algorithms topics. All solutions are written in C++ with detailed explanations, complexity analysis, and example test cases.

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📂 Directory Structure

.
├── Arrays_and_Hashing/
├── Two_Pointers/
├── Sliding_Window/
├── Stack/
├── Binary_Search/
├── Linked_List/
├── Trees/
├── Tries/
├── Heap_Priority_Queue/
├── Backtracking/
├── Graphs/
├── Dynamic_Programming/
├── Greedy/
├── Intervals/
├── Math_and_Geometry/
└── Bit_Manipulation/

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📋 Problem Index

🗂️ Arrays & Hashing

#	Title	Difficulty
1	Two Sum	Easy
49	Group Anagrams	Medium
128	Longest Consecutive Sequence	Medium
217	Contains Duplicate	Easy
238	Product of Array Except Self	Medium
242	Valid Anagram	Easy
347	Top K Frequent Elements	Medium

👆 Two Pointers

#	Title	Difficulty
11	Container With Most Water	Medium
15	3Sum	Medium
125	Valid Palindrome	Easy
167	Two Sum II	Medium

🪟 Sliding Window

#	Title	Difficulty
3	Longest Substring Without Repeating Characters	Medium
121	Best Time to Buy and Sell Stock	Easy
424	Longest Repeating Character Replacement	Medium

📚 Stack

#	Title	Difficulty
20	Valid Parentheses	Easy
155	Min Stack	Medium
739	Daily Temperatures	Medium

🔍 Binary Search

#	Title	Difficulty
33	Search in Rotated Sorted Array	Medium
153	Find Minimum in Rotated Sorted Array	Medium
704	Binary Search	Easy

🔗 Linked List

#	Title	Difficulty
21	Merge Two Sorted Lists	Easy
141	Linked List Cycle	Easy
206	Reverse Linked List	Easy

🌳 Trees

#	Title	Difficulty
100	Same Tree	Easy
104	Maximum Depth of Binary Tree	Easy
226	Invert Binary Tree	Easy
235	Lowest Common Ancestor of BST	Medium

🌲 Tries

#	Title	Difficulty
208	Implement Trie (Prefix Tree)	Medium

🏔️ Heap / Priority Queue

#	Title	Difficulty
215	Kth Largest Element in an Array	Medium
295	Find Median from Data Stream	Hard

🔄 Backtracking

#	Title	Difficulty
39	Combination Sum	Medium
78	Subsets	Medium

🕸️ Graphs

#	Title	Difficulty
133	Clone Graph	Medium
200	Number of Islands	Medium

💡 Dynamic Programming

#	Title	Difficulty
70	Climbing Stairs	Easy
198	House Robber	Medium
300	Longest Increasing Subsequence	Medium
322	Coin Change	Medium

💰 Greedy

#	Title	Difficulty
53	Maximum Subarray	Medium
55	Jump Game	Medium

📅 Intervals

#	Title	Difficulty
56	Merge Intervals	Medium
57	Insert Interval	Medium

🔢 Math & Geometry

#	Title	Difficulty
48	Rotate Image	Medium
50	Pow(x, n)	Medium

⚡ Bit Manipulation

#	Title	Difficulty
191	Number of 1 Bits	Easy
338	Counting Bits	Easy

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🚀 How to Run

Each solution file is standalone and can be compiled and executed:

g++ -std=c++17 Arrays_and_Hashing/1_two_sum.cpp -o solution
./solution

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📊 Solution Format

Every solution file includes:

• Problem statement with examples and constraints
• Approach explanation in comments
• Time & Space Complexity analysis
• Clean C++ implementation
• Runnable test cases in the main() function

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🏷️ Difficulty Legend

Badge	Meaning
Easy	Foundational problems
Medium	Core DSA patterns
Hard	Advanced techniques