30 days. That's all you need to transform from "I haven't coded in months" to "I'm ready to crush this interview."

This plan assumes you have a CS background but are rusty. If you're starting from zero, double the timeline.

Overview

Phase	Days	Focus	Goal
1	1-10	Fundamentals	Master arrays, strings, linked lists, hash maps
2	11-20	Advanced	Trees, graphs, DP, system design basics
3	21-30	Mock Interviews	Real practice, feedback, iteration

Daily commitment: 2-3 hours on weekdays, 4-5 hours on weekends.

Phase 1: Fundamentals (Days 1-10)

Day 1: Setup + Arrays

Set up your coding environment (LeetCode, local IDE)
Learn array fundamentals
Problems: Two Sum, Best Time to Buy and Sell Stock, Contains Duplicate

Day 2: Strings

String manipulation, ASCII, Unicode
Problems: Valid Anagram, Valid Palindrome, Longest Substring Without Repeating Characters

Day 3: Linked Lists

Pointer manipulation, fast/slow pointers
Problems: Reverse Linked List, Merge Two Sorted Lists, Linked List Cycle

Day 4: Hash Maps

When and why to use hash maps
Problems: Group Anagrams, Top K Frequent Elements, Subarray Sum Equals K

Day 5: Stacks & Queues

LIFO vs FIFO, monotonic stacks
Problems: Valid Parentheses, Min Stack, Daily Temperatures

Day 6: Two Pointers

Left/right pointers, sliding window intro
Problems: Two Sum II, 3Sum, Container With Most Water

Day 7: Sliding Window

Fixed vs variable window size
Problems: Maximum Average Subarray I, Longest Substring with At Most K Distinct Characters, Minimum Window Substring

Day 8: Binary Search

Classic binary search, variations
Problems: Binary Search, Search in Rotated Sorted Array, Find Minimum in Rotated Sorted Array

Day 9: Sorting & Intervals

Merge sort, quick select, interval problems
Problems: Merge Intervals, Insert Interval, Non-overlapping Intervals

Day 10: Review Day

Re-solve 5 problems you struggled with this week
Focus on writing clean, bug-free code

Phase 2: Advanced (Days 11-20)

Day 11: Trees - Basics

Binary trees, traversals (DFS, BFS)
Problems: Maximum Depth of Binary Tree, Invert Binary Tree, Binary Tree Level Order Traversal

Day 12: Trees - BST & Variants

BST properties, validation, construction
Problems: Validate BST, Kth Smallest Element in BST, Lowest Common Ancestor

Day 13: Heaps & Priority Queues

Min/max heap, heap operations
Problems: Kth Largest Element, Top K Frequent Elements (heap version), Merge K Sorted Lists

Day 14: Graphs - BFS/DFS

Graph representations, traversal
Problems: Number of Islands, Clone Graph, Pacific Atlantic Water Flow

Day 15: Graphs - Shortest Path

Dijkstra, Bellman-Ford concepts
Problems: Network Delay Time, Cheapest Flights Within K Stops, Word Ladder

Day 16: Dynamic Programming - 1D

Memoization, tabulation, state definition
Problems: Climbing Stairs, House Robber, Coin Change

Day 17: Dynamic Programming - 2D

Grid DP, string DP
Problems: Unique Paths, Longest Common Subsequence, Edit Distance

Day 18: Backtracking

Decision trees, pruning
Problems: Subsets, Permutations, Combination Sum, N-Queens

Day 19: System Design - Basics

Scalability concepts, load balancing, caching
Practice: Design URL Shortener, Design Rate Limiter

Day 20: System Design - Advanced

Databases, sharding, CAP theorem
Practice: Design Twitter Feed, Design Chat System

Phase 3: Mock Interviews (Days 21-30)

Day 21: First Mock Interview

Use Interview AiBox for AI-powered mock
Focus on communication, not just correctness
Review recording, note weak points

Day 22: Address Weaknesses

Re-practice problem types you struggled with
Focus on speed and clarity

Day 23: Second Mock Interview

Different problem types (try a graph problem)
Practice explaining trade-offs

Day 24: Behavioral Prep

Prepare 5 STAR stories
Practice "Tell me about yourself" and "Why this company?"

Day 25: Third Mock Interview

Full interview simulation (45 min coding + 15 min behavioral)
Time yourself strictly

Day 26: System Design Practice

Mock system design interview
Practice drawing diagrams and explaining

Day 27: Fourth Mock Interview

Focus on your weakest area
If arrays are weak, do an array-heavy mock

Day 28: Fifth Mock Interview

Mix of easy, medium, and one hard problem
Practice handling "I don't know" moments gracefully

Day 29: Final Review

Review all notes, re-solve 3 problems from each phase
Rest well, don't overdo it

Day 30: Light Practice + Mindset

Solve 2 easy problems to build confidence
Visualize success
Prepare your interview outfit and logistics

Daily Routine Template

Weekdays (2-3 hours):

30 min: Review yesterday's concepts
90 min: Solve 2-3 new problems
30 min: Review solutions, understand patterns

Weekends (4-5 hours):

60 min: Learn new concept
180 min: Solve 4-5 problems
60 min: Mock interview or review

Tools & Resources

Resource	Use For
Interview AiBox	Mock interviews with AI feedback
LeetCode	Problem practice
NeetCode	Video explanations
System Design Primer	System design prep

FAQ

What if I can't finish all problems?

Focus on understanding patterns over quantity. 100 problems deeply understood beats 300 problems shallowly memorized.

Should I do Easy problems?

Yes, especially early on. They build confidence and reinforce patterns. But move to Medium quickly—most interview questions are Medium level.

What about Hard problems?

Attempt them in Phase 2-3, but don't stress. Most interviews have at most one Hard problem. Focus on Medium mastery first.

How do I stay motivated?

Track progress visually. Check off each day. Celebrate small wins. Use mock interviews to see your improvement.

Next Steps

Start today. Don't wait for the "perfect time."
Use Interview AiBox for mock interviews—it's the closest to real interview pressure.
Stay consistent. 30 days of steady practice beats one weekend of cramming.

Your dream job is 30 days away. Start now.

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