Study Plan
The 4-Week Coding Interview Plan
A pattern-first plan that takes you from Arrays to Mock Interviews in 28 days. Target: 65 problems, all filtered by importance — no noise.
Week 1 — Foundations
Arrays, strings, and the patterns that crack 40% of Easy questions.
Spend 30 min on each problem. If you cannot solve it, read the approach — then implement from scratch the next day without looking.
| Days | Patterns |
|---|---|
| Mon – Tue | |
| Wed – Thu | |
| Fri – Sat | |
| Sun | Rest & Review |
Week 2 — Core Data Structures
Stacks, heaps, and linked lists — the backbone of Medium-difficulty interviews.
Start timing yourself this week. Medium problems should take under 25 minutes. If a problem takes longer, note why and add it to your review queue.
| Days | Patterns |
|---|---|
| Mon – Tue | |
| Wed | |
| Thu – Fri | |
| Sat | |
| Sun | Rest & Review |
Week 3 — Trees, Graphs & DP
The hardest week. Slow down on DP — correctness beats speed.
For every DP problem: write the state definition in plain English before writing code. If you cannot explain dp[i] in one sentence, redefine the state.
| Days | Patterns |
|---|---|
| Mon – Tue | |
| Wed | |
| Thu – Fri | |
| Sat | |
| Sun | Rest & Review |
Week 4 — Review & Mock Interviews
Polish, speed, and communication — the final mile.
Communication is 50% of the score. Narrate your thought process out loud: "I'm reaching for a hash map here because..." before you write a single line.
| Days | Patterns |
|---|---|
| Mon | Rest & Review |
| Tue – Wed | |
| Thu | Rest & Review |
| Fri | Rest & Review |
| Sat | Rest & Review |
| Sun | Rest & Review |
Must-Know Problems
High-frequency problems that appear most often in interviews. Solve these before anything else.
| # | Problem | Difficulty | Solution | Link |
|---|---|---|---|---|
| 01 | Longest Substring Without Repeating Characters
#String
#Hash Map
#Sliding Window | Medium | Solution | |
| 02 | Minimum Window Substring
#String
#Hash Map
#Sliding Window | Hard | Solution | |
| 03 | Two Sum II - Input Array Is Sorted
#Array
#Two Pointers
#Binary Search | Medium | Solution | |
| 04 | 3Sum
#Array
#Two Pointers
#Sorting | Medium | Solution | |
| 05 | Container With Most Water
#Array
#Two Pointers
#Greedy | Medium | Solution | |
| 06 | Trapping Rain Water
#Array
#Two Pointers
#Stack | Hard | Solution | |
| 07 | Valid Palindrome
#String
#Two Pointers | Easy | Solution | |
| 08 | Remove Duplicates from Sorted Array
#Array
#Two Pointers | Easy | Solution | |
| 09 | Binary Search
#Array
#Binary Search | Easy | Solution | |
| 10 | Search in Rotated Sorted Array
#Array
#Binary Search | Medium | Solution | |
| 11 | Find Minimum in Rotated Sorted Array
#Array
#Binary Search | Medium | Solution | |
| 12 | Subarray Sum Equals K
#Array
#Hash Map
#Prefix Sum | Medium | Solution | |
| 13 | Product of Array Except Self
#Array
#Prefix Product | Medium | Solution | |
| 14 | Two Sum
#Array
#Hash Map | Easy | Solution | |
| 15 | Group Anagrams
#String
#Hash Map
#Sorting | Medium | Solution | |
| 16 | Top K Frequent Elements
#Array
#Hash Map
#Heap | Medium | Solution | |
| 17 | Valid Anagram
#String
#Hash Map
#Sorting | Easy | Solution | |
| 18 | Longest Consecutive Sequence
#Array
#Hash Set | Medium | Solution | |
| 19 | Valid Parentheses
#String
#Stack | Easy | Solution | |
| 20 | Min Stack
#Stack
#Design | Medium | Solution |
52-Week CS Fundamentals Comprehensive Masterplan
Coding questions only account for half of tier-1 evaluations. This structured 52-week masterplan ensures complete mastery across Operating Systems, DBMS, Computer Networks, and OOP with rigorous numerical drilling and articulation practice.
What each of the four subjects covers, how they connect, and which companies weight which.
Read the Skills Matrix end to end. Mark what you already know honestly.
Kernel, system calls, process versus thread, states, context switching, IPC, all scheduling algorithms.
Solve 40 scheduling numericals. Draw the process state diagram from memory five times.
Race conditions, mutex, semaphore, deadlock and its four conditions, Banker's, paging, virtual memory, page replacement, thrashing.
Solve 40 page replacement and Banker's numericals. Write producer-consumer with semaphores.
ER model, keys, functional dependencies, 1NF through BCNF, decomposition, lossless join.
Normalise 20 tables to BCNF showing every step. Draw 10 ER diagrams from written scenarios.
All join types, subqueries, aggregates, window functions, ACID, isolation levels, locking, serialisability, indexing.
Solve 100 SQL problems. Work through 20 serialisability and isolation questions.
OSI and TCP/IP, all seven layers, devices per layer, error detection, flow control, switching, MAC and ARP.
Recite the seven layers with protocols daily until automatic. Solve 30 CRC and sliding window problems.
IPv4, subnetting, CIDR, routing, NAT, TCP versus UDP, handshake, congestion control, DNS, HTTP, TLS.
Solve 50 subnetting numericals. Walk through the full URL-to-page path ten times, out loud.
Four pillars, inheritance types, polymorphism, abstract versus interface, SOLID, patterns, coupling and cohesion.
Implement the four pillars in your language. Write singleton, factory, observer and strategy from scratch.
Where these concepts appear in real code: threads in your backend, indexes in your queries, TCP in your API calls.
For every major concept, find where it appears in a project you have built. Write it down.
Scheduling, page replacement, disk scheduling, subnetting, CRC, normalisation, serialisability.
Two hours weekly on timed numericals only. Written rounds are mostly numericals under time pressure.
Work through every question on the Most Asked sheet until each answer is automatic.
Answer each question out loud, timed, without notes. Record yourself for the ones you fumble.
Explaining clearly, giving examples, handling follow-ups, admitting what you do not know gracefully.
Two mocks weekly focused only on CS core. Have someone interrupt you with follow-ups.
Which subjects your target companies weight, their written test format, their past question patterns.
Study the Where It Is Asked sheet. Solve past papers for your target companies.
Spaced revision of everything. CS core fades fast if untouched for a month.
Weekly revision of one subject in rotation. Re-answer the Most Asked sheet monthly.
Ready to start?
Open Week 1 — Sliding Window is the best first pattern to lock in.