For coding interviews
Spot the pattern behind problems you've never seen.
Most coding-interview problems use one of 25 patterns. This 727-page book teaches each one once, shows the clues that give it away, and solves it in Java, Python, C++ and JavaScript.
₹299regular price ₹599
Launch price · First 100 buyers
That's about ₹12 a pattern, or under ₹1 a page.
- Tested code1,464 test runs, all passing
- Made for phoneslaid out for small screens
- Your own copywith a unique ID
- 50worked problems
- 277practice problems
- 25one-page revision cards
- 4 languagesJava, Python, C++, JS
- 727 pagesPDF for phone or laptop
- 25 patternsranked by real data
- 50 worked problemssolved step by step
- 277 practice problemsEasy to Hard
- 4 languagesJava, Python, C++, JavaScript
Sound familiar?
Solved 300 problems, and a new one still makes you freeze?
Why it happens
You learned answers, not patterns. A new question looks unfamiliar, so the answers you memorised don't help.
What fixes it
Learn each pattern's logic once. Learn the clues in a question that point to it. Then write it in any language.
- 1Spot itRecognition cues and a flowchart tell you which of the 25 patterns a question needs.
- 2Plan itA short pseudocode template, traced step by step with diagrams.
- 3Code itTested solutions in Java, Python, C++ and JavaScript that paste straight into LeetCode.
Questions change. Patterns don't. Spot the right one fast, and give yourself a better chance at the offer.
regular price ₹599 · Launch price · First 100 buyers
Why you can trust it
Every solution was tested before it was printed.
The code, the diagrams and the chapter order all come from real test runs and real counts.
- 1,464 test runs, all passing50 problems in 4 languages. The code uses LeetCode's exact method signatures, so it pastes straight in.
- Ordered by real data213 unique problems from Blind 75, NeetCode 150 and Grind 169. Chapters 1–12 cover 68.1% of them.
- Diagrams from real runsEvery dry-run figure is drawn from logs of the tested code, so the pictures match the code.
- Checked before releaseFinal checks passed 7 of 7, including 368 verified problem links and a source for every number.
regular price ₹599 · Launch price · First 100 buyers
Look inside
See the pages before you buy.
Every chapter follows the same 11 steps, so you always know where you are. Tap a page to read it full size.
- Name the pattern a new question needs, from the words in the question.
- Turn each pattern into code from a short template, in Java, Python, C++ or JavaScript.
- Trace your solution step by step, and state its time and space complexity.
- Avoid the common mistakes and edge cases for each pattern.
- Answer the follow-up questions interviewers ask next.
- Follow a plan on interview day: clarify, examples, brute force, optimise, code, test, complexity.
- 1Tree DFS
- 2Hashing & Frequency Counting
- 3Graph BFS/DFS
- 4Two Pointers
- 51-D Dynamic Programming
- 6Matrix & Simulation
- 7Linked-List Reversal & Rewiring
- 8Heaps: Top-K, K-way Merge, Two Heaps
- 9Backtracking
- 10Stack: Matching & Parsing
- 11Binary Search
- 122-D DP: Grids & Strings
- 13Greedy
- 14Bit Manipulation
- 15Intervals: Merge & Sweep Line
- 16Sliding Window
- 17Fast & Slow Pointers
- 18Knapsack DP
- 19Union-Find
- 20Tree BFS (Level Order)
- 21Prefix Sum + Hash Map
- 22Trie
- 23Topological Sort
- 24Monotonic Stack & Deque
- 25Shortest Paths: Dijkstra & Bellman-Ford
Ranked by how many of 213 unique problems from Blind 75, NeetCode 150 and Grind 169 use each pattern. Chapters 1–12 cover 68.1% of the set.
The ranking measures how much of these prep lists each pattern unlocks. It does not measure how often companies ask a pattern.
regular price ₹599 · Launch price · First 100 buyers
Student route
Students
30 days, about 3 hours a day, one chapter a day, with a review day every 6 chapters.
6-week steady route
Working professionals
About 1 hour on weekdays and 3 hours on weekend days.
14-day crash route
Interview already booked
Related chapters paired by day.
Service-based track
Mass-recruiter coding rounds
High-relevance patterns first: Hashing, Two Pointers, Simulation.
Under 7 days
Emergencies
Only the Cheat Code cards, the Pattern Recognition Drill and the interview-day playbook.
regular price ₹599 · Launch price · First 100 buyers
- 1OpenerThe pattern's one-line cheat code, its rank, reading routes and a skip test.
- 2IntuitionA real-world comparison and a diagram.
- 3Recognition cuesThe exact words that signal this pattern, and when not to use it.
- 4Pseudocode templateShort steps tagged [S1], [S2] and so on.
- 5Two worked problemsThe brute-force idea, pseudocode, a dry-run diagram, code in all four languages, and the time and space cost.
- 6VariationsThe common twists on the core problem.
- 7Common mistakesMistakes and edge cases to check before you submit.
- 8Interviewer follow-upsThe questions that come next, with model answers.
- 9Practice ladder8–12 LeetCode problems, Easy to Hard.
- 10Cheat Code cardOne page you can screenshot for revision.
- 11BridgeHow this pattern leads into the next chapter.
Who it's for
Pick your route and start today.
Short sentences, and every term explained where it first appears. You only need one of the four languages.
Students
Preparing for campus placements or a first job.
Student route: 30 days, one chapter a day.
Working developers
Switching jobs, short on time and rusty on DSA.
6-week steady route: about 1 hour on weekdays.
Service-based company rounds
Facing TCS, Infosys, Wipro or Accenture-style coding rounds.
Service-based track: Hashing, Two Pointers and Simulation first.
Interview in under 7 days
No time for the full book.
Emergency route: Cheat Code cards, the Drill and the Playbook.
regular price ₹599 · Launch price · First 100 buyers
Everything you get
Everything in the book, for ₹299
- 25 pattern chapters, each in the same 11 steps
- 50 worked problems, solved in all four languages
- 277 practice problems, Easy to Hard
- 25 one-page Cheat Code cards for quick revision
- The Pattern Recognition Flowchart
- A 30-problem Pattern Recognition Drill, with answers
- An interview-day playbook: what to say at each step
- 5 study routes, from 30 days down to under 7 days
- Your own copy of the 727-page PDF, with a unique ID
₹299regular price ₹599
Launch price · First 100 buyers
That's about ₹12 a pattern, or under ₹1 a page.
Questions
Still deciding? Read this first.
I've already solved a lot of LeetCode. Do I need this?
If you can solve a problem but can't name its pattern, a new question can still stop you. This book teaches the pattern behind the problems. Already strong on a pattern? Each chapter has a skip test: if you solve its problem in 20 minutes with no hints, read only the cues, the follow-ups and the card.
I only know one of the four languages. Is that enough?
Yes. Each pattern is taught once in pseudocode, then solved in Java, Python, C++ and JavaScript. Read the one you use and skip the rest.
My interview is next week. Is it too late?
No. The under-7-days route uses only the 25 one-page Cheat Code cards, the 30-problem Pattern Recognition Drill and the interview-day playbook.
Why pay for a PDF when problem lists are free?
Free lists give you problems. This book gives you the 25 patterns behind them: the clues that reveal each one, a template, and tested code in four languages. The order comes from 213 problems on three popular lists, so you learn what unlocks the most first.
Can I read it on my phone?
Yes. The pages are laid out for phones, tablets and laptops, and no code line is longer than 56 characters.
What exactly do I get?
One 727-page PDF of about 17 MB, with working bookmarks and links. It is your own copy, with a unique ID.
How do I pay?
Tap any buy button on this page. It opens the Superprofile checkout, where you pay.
How was the chapter order chosen?
Blind 75, NeetCode 150 and Grind 169 were merged into 213 unique problems, and each pattern is ranked by how many of them use it. This shows how much of those lists a pattern unlocks, not how often companies ask it.
What is the unique copy ID?
Each buyer gets their own copy with a unique ID (DT-XXXX-XXXX). The copy is encrypted against editing and carries hidden fingerprints, so a leaked copy can be traced back to its buyer.
Found a mistake, or have a question?
Write to contact@developertype.com for errata and updates.
regular price ₹599 · Launch price · First 100 buyers
More interview notes are on the way
Interview notes for Java, JavaScript, Python and C++ are next.
JavaComing soon
JavaScriptComing soon
PythonComing soon
C++Coming soon
Questions change. Patterns don't.
Learn the 25 patterns behind most coding-interview problems at the launch price of ₹299.
Not affiliated with or endorsed by LeetCode.