🧠 DSA Journey — Zulaikha Ashiq

A collection of my solutions and notes while practicing data structures and algorithms.

🌿 Overview

Languages used: Java Currently focusing on: Arrays, Strings, and Dynamic Programming Goal: 200+ solved problems by mid-2026

🗺️ Learning Path

New to DSA? Check out LEARNING_PATH.md for a recommended order to tackle topics, building from foundations to advanced concepts.

The path is organized in 6 phases:

1. Foundations - Patterns, Math basics, Arrays basics
2. Core Data Structures - Strings, Linked Lists, Stack, Queue, Deque
3. Core Algorithms - Sorting, Searching, Recursion
4. Advanced Techniques - Hashing, Bit Manipulation, Optimization
5. Specialized Topics - Matrix, Advanced Math, Complex DS problems
6. Mastery - Dynamic Programming, Cross-topic problems

📁 Repository structure

All problems are organized by topic, then by difficulty. Filenames match public class names for easy running.

<topic>/
  basic/                # legacy bucket, gradually being redistributed
  easy/                 # warm-up, straightforward loops, basic DS ops
  medium/               # two-pointers, sliding window, hashing tricks, binary search variants
  hard/                 # non-trivial invariants, optimizations, or multi-step reductions

arrays/, strings/, math/, bit-manipulation/, matrix/, linked-list/,
queue/, stack/, deque/, hashing/, patterns/, searching/, sorting/, recursion/, dp/

Examples:

• arrays/easy/ReverseArray.java
• strings/medium/LongestSubstringDistinctCharsEfficient.java
• searching/hard/MedianOfTwoSortedArrays.java

🏆 Progress Tracker

Platform	Solved	Profile Link
LeetCode	26	LeetCode Profile

▶️ How to run

• Windows (CMD):
  • run-java.cmd path\\to\\File.java
• Windows (PowerShell):
  • ./run-java.ps1 path/to/File.java
• Manual (any shell):
  • javac path/to/File.java
  • cd path/to && java ClassName

Notes:

• Each file is standalone with its own main(String[] args) and no packages.
• The scripts compile and run in the file's directory so default-package classes work.

🔖 Naming conventions

• Filenames are PascalCase and match the public class name (Java requirement).
• Problem names are descriptive, e.g. SearchInRotatedSortedArray, TwoStacksInArray, SieveOfEratosthenes.

🎯 Difficulty rubric (relative)

• Easy
  • Straightforward iterations, simple math/conditions
  • Basic DS operations (insert/delete/traverse)
• Medium
  • Sliding window, two-pointers, hash-based techniques
  • Binary search variations, matrix traversals, efficient duplicates handling
• Hard
  • Non-trivial invariants or data structures; multi-phase logic
  • Problems where correctness depends on careful edge-case reasoning or optimal asymptotics

This rubric is applied by comparing solutions in the repo (not platform tags).

add JUnit tests in your local/GitHub repository