📘 Data Structures & Algorithms in Java

Welcome to my DSA Journey — a curated notebook of hand-written, optimized solutions to the most popular problems on LeetCode, solved using Java.

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🚀 DSA Dashboard

Category	Status
🧱 Arrays
🔤 Strings
🔗 Linked List
🧵 Stack & Queue
🌳 Trees	9
🌐 Graphs
🔑 HashMap
➕ Prefix Sum
🪟 Sliding Window
🧭 Two Pointer
⚡ Greedy
🧩 DP

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🧱 Array (45) Two Sum Two Sum II Remove Duplicates Remove Element Squares of a Sorted Array Container With Most Water Find Duplicate Find Peak Element Search Insert Position Maximum Subarray Maximum Product Subarray Binary Search Find First & Last Position Search in Rotated Array Kth Largest Element Find Pivot Index Product of Array Except Self Find Middle Index Find Highest Altitude Range Sum Query Contains Duplicate Majority Element Unique Number of Occurrences Best Time to Buy and Sell Stock Best Time to Buy and Sell Stock II Check if Array Sorted & Rotated Concatenation of Array Intersection of Two Arrays Intersection of Two Arrays II Longest Consecutive Sequence Max 69 Number Maximum Average Subarray Minimum Size Subarray Sum Missing Number Palindrome Number Running Sum Single Number Subarray Sum Equals K Find Duplicate Number Rotate Array Move Zeros Maximum Product of Three Numbers Trapping Rain Water (Add more) (Add more)

## 🔤 String (21) 1. Reverse String 2. Reverse String II 3. Reverse Only Letters 4. Reverse Vowels 5. Roman to Integer 6. Valid Parentheses 7. Valid Palindrome 8. Valid Anagram 9. First Occurrence in a String 10. Is Subsequence 11. Word Arrays Equivalent 12. Longest Substring Without Repeating Characters 13. Longest Common Prefix 14. First Unique Character 15. Find the Difference 16. To Lower Case 17. FizzBuzz 18. Words Containing Character 19. Rotate String 20. Group Anagrams 21. Valid Word

🔗 Linked List (13) Reverse LL (Iterative) Reverse LL (Recursive) Middle of Linked List Merge Two Sorted LL (Recursive) Merge Two Sorted LL (Iterative) Delete Node Intersection of Two Linked Lists Delete Middle Node Remove Duplicates (Sorted) Remove Nth Node from End Linked List Cycle Palindrome Linked List Add Two Numbers 🧵 Stack & Queue (15) Evaluate Reverse Polish Notation Remove All Adjacent Duplicates In String Baseball Game Clear Digits Valid Parentheses Next Greater ElementI Implement Queue Using Stacks Implement Stack Using Queues Daily Temperatures Remove Duplicate Letters Longest Valid Parentheses Largest Rectangle in Histogram Make the String Great Time Needed to Buy Tickets Number of Students Unable to Eat Lunch 🌳 Tree (9) Same Tree Preorder Traversal Postorder Traversal Level Order Convert Sorted Array to BST Convert Sorted List to BST Inorder Traversal Path Sum Level Order II

✨ Why This Repo Exists

To track progress, revise patterns, and build a strong foundation in DSA for FAANG-level interviews.

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