Mastering coding interviews through patterns, data structures, and deep understanding
A curated, structured journey to becoming technically strong and interview-ready.
This repo is not just a solution bank. It's a personal roadmap to:
- ✅ Practic by problem-solving patterns, not just topics.
- ✅ Improve code quality and Java syntax fluency.
- ✅ Develop true algorithmic thinking and systemized approaches.
- ✅ Make revision faster with clean explanations and categorizations.
| 🧩 Pattern | 💡 When to Use |
|---|---|
| Two Pointers | When scanning from both ends or moving inwards |
| Sliding Window | Substrings, subarrays, longest/repeating patterns |
| Prefix Sum / Diff | Range-based queries, cumulative totals |
| Stack / Monotonic | Previous/next greater elements, parsing expressions |
| Backtracking | Permutations, combinations, constraint-based paths |
| Binary Search | Sorted input, finding boundaries, search space |
| Dynamic Programming | Overlapping subproblems and optimal substructure |
| Union Find / DSU | Disjoint components, connectivity problems |
| Structure | Use Cases & Application Areas |
|---|---|
| Arrays | Sorting, partitioning, searching, prefix-based logic |
| HashMaps / Sets | Fast lookups, frequency counts, uniqueness checks |
| Stacks / Queues | Parsing, order retention, monotonic sequences |
| Linked Lists | Pointer manipulation, reversal, merging |
| Trees | DFS, BFS, recursion, tree building |
| Graphs | Topo sort, shortest path, DFS/BFS traversals |
| Heaps / PriorityQ | Top K problems, streaming data, merging sorted lists |
| Tries | Prefix-based searching, autocomplete systems |
| 1D/2D DP Arrays | Grid problems, subset sums, palindromes |
This repo is optimized for:
📘 Learning Efficiency
- Each problem is tied to a common pattern and includes annotated code
- Java-specific syntax tricks and best practices explained
🧠 Depth Over Breadth
- Instead of covering 1000 problems, we focus on the ones that build intuition
- Strategic repetition of concepts in varying problem forms
💼 Interview Readiness
- Emphasis on what companies ask most
- Strong focus on patterns like Two Pointers, Sliding Window, Recursion, and DP
Each uploaded solution follows this format:
- 🔖 Problem Tag: e.g., Arrays, HashMap, Greedy, etc.
- 🧠 Approach Summary: What’s the strategy and why it works
- 🕒 Time & Space Complexity: Always stated for clarity
- ✅ Java Code: Clean, readable, and commented
- 🧩 Pattern Mapped: So you can link it to similar questions
- Visual mind-map of pattern links 🔗
- PDF guide with patterns and examples 📄
- Java syntax mini-cheatsheet 🧾
- Notes folder with concept breakdowns 📘
- Test cases for selected problems ✅
This is currently a solo project for structured learning. If you're interested in:
- Sharing similar learning journeys
- Suggesting patterns or improvement ideas
- Collaborating on the PDF + visual roadmap
Feel free to open an issue or connect below 👇