🚀 DSA_WITH_PATTERNS

Solving DSA Leetcode Problems Daily in JAVA

A structured repository dedicated to solving Data Structures & Algorithms problems in Java using the most important coding patterns and approaches.

This repository focuses on:

• Daily DSA practice
• Pattern-based problem solving
• Writing clean and optimized Java solutions
• Learning multiple approaches from brute force to optimal
• Building strong interview preparation skills

The patterns followed in this repository are inspired by the DSA Pattern Sheet provided in the roadmap. :contentReference[oaicite:0]{index=0}

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📌 Goals

• Solve DSA problems consistently
• Master common coding interview patterns
• Improve logical thinking and optimization skills
• Learn time and space complexity analysis
• Strengthen Java problem-solving abilities

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🛠️ Tech Stack

• Language: Java
• Platform: LeetCode
• IDE: IntelliJ IDEA / VS Code
• Version Control: Git & GitHub

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🧠 Problem Solving Approach

Each problem may contain:

1️⃣ Brute Force Approach

• Basic intuitive solution
• Easy to understand
• Higher complexity

2️⃣ Better Approach

• Improved using data structures or optimized logic

3️⃣ Optimal Approach

• Best possible solution
• Efficient time and space complexity

Each solution includes:

• Explanation
• Dry run / intuition
• Time Complexity
• Space Complexity
• Clean Java implementation

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📚 DSA Patterns Covered

🔹 Two Pointers

• Pair problems
• Sorted array techniques
• Triplets / Quadruplets
• Dutch National Flag

🔹 Fast & Slow Pointers

• Cycle detection
• Linked List problems
• Middle node problems

🔹 Sliding Window

• Fixed window
• Dynamic window
• Substring problems

🔹 Kadane’s Algorithm

• Maximum subarray variations
• Circular subarrays
• Product subarrays

🔹 Prefix Sum

• Range sums
• Subarray sum problems
• Running sum techniques

🔹 Merge Intervals

• Interval merging
• Overlapping intervals
• Meeting room problems

🔹 Linked List Reversal

• Reverse linked lists
• K-group reversal
• Sublist reversal

🔹 Stack Pattern

• Monotonic stack
• Parentheses problems
• Next greater element

🔹 HashMap Pattern

• Frequency counting
• Character mapping
• Lookup optimization

🔹 Binary Search Pattern

• Search space reduction
• Rotated arrays
• Answer-based binary search

🔹 Heap / Priority Queue

• Top K elements
• Kth smallest/largest
• Two heaps pattern

🔹 Greedy Algorithms

• Scheduling problems
• Resource optimization
• Heap + greedy combinations

🔹 Recursion & Backtracking

• Permutations
• Combinations
• Recursive traversal
• Decision trees

🔹 Tree Patterns

• DFS Traversals
• BFS Traversals
• BST problems
• Path sum problems
• Tree construction

🔹 Graph Patterns

• BFS & DFS
• Shortest path algorithms
• Topological sort
• Dijkstra’s Algorithm
• Union Find concepts

🔹 Dynamic Programming

• Memoization
• Tabulation
• 1D & 2D DP
• Optimization problems

The repository structure and patterns are inspired by the uploaded DSA pattern roadmap. :contentReference[oaicite:1]{index=1}

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📂 Repository Structure

DSA_WITH_PATTERNS/
│
├── Arrays/
├── Strings/
├── TwoPointers/
├── SlidingWindow/
├── PrefixSum/
├── LinkedList/
├── Stack/
├── Queue/
├── Trees/
├── BST/
├── Graphs/
├── Heap/
├── Greedy/
├── Recursion/
├── Backtracking/
├── DynamicProgramming/
├── BinarySearch/
└── Patterns/