🧠 DSA Journey in Java

Pattern-Based Problem Solving • Quantitative Progress Tracking

I build solutions that are earned, not copied. This repository tracks my transition from brute-force attempts to structured pattern recognition.

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📂 Navigation & Connectivity

Quick access to my work and professional profiles:

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📊 Performance Metrics (As of January 2026)

Metric	Baseline (Nov 2025)	Current (Jan 2026)	Delta
LeetCode Acceptance	52.9%	76.23%	+23.33% 📈
LeetCode Problems	~35	45	+28.6%
Unique Problems (Total)	~35	68	+94% 🚀
Total Implementations	~45	95	Multi-solution mastery
Solving Strategy	Brute-Force Guessing	Pattern-First Methodology	✅ Systematic

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🏗️ Repository Structure

A clean, logical hierarchy for easy code review and navigation.

DSA-in-Java/
├── 📂 Patterns/            # 16 unique problems (17 files, Pattern2=Pattern3)
├── 📂 Basic Maths/         # 31 unique problems (39 files with optimizations)
│   ├── 📁 Array_Operations/  # 6 problems (9 files: Duplicate×3, SortedSquares×2)
│   ├── 📁 Divisors/          # 3 problems (5 files: Divisors×2, PerfectNumber×2)
│   ├── 📁 HCF_LCM/           # 2 problems (3 files: LCM×2)
│   ├── 📁 Miscellaneous/     # 7 problems (8 files: UniqueChar×2)
│   ├── 📁 Modulus_Digit/     # 9 problems (10 files: HappyNumber×2)
│   └── 📁 Sieve_Prime/       # 4 problems (all unique)
├── 📂 Recursion/           # 15 unique problems (dual approaches in same files)
│   ├── Fibonacci, Tribonacci, Climbing Stairs (iterative + recursive)
│   ├── Pascal's Triangle, Power(x,n) (both approaches commented)
│   └── Reverse Array/String (3 methods in Reverse_Array.java)
├── 📂 Codeforces/          # 3 unique problems (competitive programming)
│   ├── 📁 800-1000/          # 2 problems (Domino Piling, Watermelon)
│   └── 📁 1001-1500/         # 1 problem (Laptops - sorting + greedy)
├── 📂 JAVA COLLECTIONS/    # 15 reference files (NOT problems)
└── 📂 Misc/                # 3 unique problems (Bank, FizzBuzz, Palindrome variant)

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📈 Curriculum Status

Module	Status	Problems Solved	Key Achievement
Patterns	✅ COMPLETE	17/17	Formula derivation mastery
Basic Maths	✅ COMPLETE	17/17 (Striver) + 14 additional	Multiple optimization approaches
Basic Recursion	✅ COMPLETE	14/14	Dual implementations (iterative + recursive)
Basic Hashing	✅ COMPLETE	16/16	HashMap mastery + frequency counting
JAVA Collections	📚 Reference	0 (not problems)	Deep understanding of Java internals
Codeforces	🟡 Started	3	Competitive programming practice
Sorting	⚪ NEXT	0/14	Starting after exam break
Binary Search	⚪ Upcoming	0/47	Planned after Sorting

🎯 Section 1: BASICS - CRUSHED ✅

COMPLETE: 47/47 Striver reference problems + 17 patterns + 4 bonus = 68 unique problems total

• ✅ Basic Maths: 17/17 (100%)
• ✅ Basic Recursion: 14/14 (100%)
• ✅ Basic Hashing: 16/16 (100%)
• ✅ Patterns: 17/17 (100%)

Next Section: Sorting Techniques (7 Striver + 7 Additional = 14 total) - Starting March 6, 2026 after exams

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🎯 Solution Quality Metrics

What makes this different from tutorial code:

• 12 problems with multiple approaches - Evolution from brute force to optimal visible in code
• 8 recursion files with dual implementations - Both iterative and recursive in same file
• Optimization examples: Duplicate detection (O(n log n)→O(n)), Perfect Number (O(n)→O(√n)), Sorted Squares (O(n log n)→O(n))

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💬 Code Standards

Every solution in this repo adheres to Interview-Grade Standards:

• Meaningful Naming: Variables like leftPtr, sumTotal, and isFound replace i, s, and f.
• Complexity Comments: Every file includes a header with Time Complexity () and Space Complexity () analysis.
• Local Validation: Code is only committed after passing a custom local test rig including edge cases.

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"In a world of copy-paste, I ship solutions I actually understand."

68 Unique Problems • 95 Total Implementations • 12 Multi-Solution Problems

Maintained by Yuvraj Sarathe • B.Tech Cyber Security Student

Last System Update: January 2025