# 90 Days Preparation Schedule **Month 1: Foundations and Basics** Week 1-2: Data Structures and Algorithms (Basics) Week 3-4: Algorithms (Intermediate) **Month 2: Intermediate Topics and System Design** Week 5-6: Data Structures and Algorithms (Intermediate) Week 7-8: Advanced System Design and Final Preparation **Month 3: Advanced Topics and Mock Interviews** Week 9-10: Comprehensive Review and Mock Interviews

Day	Focus Area	Problems
Day 1	Arrays	Two Sum, Reverse String, Maximum Subarray, Merge Intervals
Day 2	Arrays	Contains Duplicate, Best Time to Buy and Sell Stock, Product of Array Except Self, Search in Rotated Sorted Array
Day 3	Strings	Valid Anagram, Longest Substring Without Repeating Characters, Longest Palindromic Substring, Group Anagrams
Day 4	Linked Lists	Reverse Linked List, Merge Two Sorted Lists, Linked List Cycle, Remove Nth Node From End of List
Day 5	Linked Lists	Add Two Numbers, Swap Nodes in Pairs, Copy List with Random Pointer, LRU Cache
Day 6	Stacks & Queues	Valid Parentheses, Min Stack, Evaluate Reverse Polish Notation, Implement Queue using Stacks
Day 7	Stacks & Queues	Daily Temperatures, Sliding Window Maximum, Basic Calculator, Decode String
Day 8	Hash Tables	Two Sum with HashMap, Group Anagrams, Top K Frequent Elements, Longest Consecutive Sequence
Day 9	Hash Tables	Valid Sudoku, Word Pattern, Isomorphic Strings, Minimum Window Substring
Day 10	Hash Tables	Happy Number, Contiguous Array, Subarray Sum Equals K, Maximum Size Subarray Sum Equals K
Day 11	Sorting & Searching	Merge Sort, Quick Sort, Binary Search, Search a 2D Matrix
Day 12	Sorting & Searching	Find Peak Element, First Bad Version, Median of Two Sorted Arrays, Find Minimum in Rotated Sorted Array
Day 13	Recursion & Backtracking	Subsets, Permutations, Combination Sum, Palindrome Partitioning
Day 14	Recursion & Backtracking	Word Search, N-Queens, Generate Parentheses, Letter Combinations of a Phone Number
Day 15	Dynamic Programming (Intro)	Climbing Stairs, House Robber, Maximum Subarray, Longest Common Subsequence
Day 16	Dynamic Programming (Intro)	Coin Change, Longest Increasing Subsequence, Word Break, Partition Equal Subset Sum
Day 17	Graphs & Trees (Basics)	Binary Tree Inorder Traversal, Symmetric Tree, Maximum Depth of Binary Tree, Path Sum
Day 18	Graphs & Trees (Basics)	Validate Binary Search Tree, Lowest Common Ancestor of a Binary Search Tree, Serialize and Deserialize Binary Tree, Invert Binary Tree
Day 19	Graphs & Trees (Basics)	Number of Islands, Clone Graph, Course Schedule, Pacific Atlantic Water Flow
Day 20	Review	Review all topics from Weeks 1-2, reattempt difficult problems, summary notes
Day 21	Review	Review all topics from Weeks 1-2, reattempt difficult problems, summary notes
Day 22	Advanced Linked Lists & Trees	Flatten a Multilevel Doubly Linked List, Binary Tree Zigzag Level Order Traversal, Construct Binary Tree from Preorder and Inorder Traversal, Kth Smallest Element in a BST
Day 23	Advanced Linked Lists & Trees	Populating Next Right Pointers in Each Node, Lowest Common Ancestor of a Binary Tree, Binary Tree Maximum Path Sum, Binary Tree Right Side View
Day 24	Heaps & Priority Queues	Kth Largest Element in an Array, Merge k Sorted Lists, Find Median from Data Stream, Top K Frequent Words
Day 25	Heaps & Priority Queues	Sliding Window Median, Trapping Rain Water II, Employee Free Time, Task Scheduler
Day 26	Advanced Graph Algorithms	Course Schedule II, Network Delay Time, Alien Dictionary, Word Ladder II
Day 27	Advanced Graph Algorithms	Minimum Cost to Reach Destination in Time, Find Eventual Safe States, Redundant Connection II, Reconstruct Itinerary
Day 28	System Design Basics	Read System Design Primer on GitHub, watch introductory system design videos
Day 29	System Design Basics	Design URL Shortener, Design Twitter, justify design decisions, focus on scalability
Day 30	System Design Basics	High-level components, databases, APIs, load balancing
Day 31	System Design Basics	Design systems considering storage requirements, indexing, partitioning
Day 32	Distributed Systems	Understand microservices, distributed caching, consensus algorithms, read up on CAP theorem
Day 33	Distributed Systems	Design YouTube, Design Uber, focus on distributed data management, fault tolerance
Day 34	Distributed Systems	Practice designing distributed systems with high availability, low latency
Day 35	Behavioral Questions	Learn STAR method, prepare responses for common behavioral questions
Day 36	Behavioral Questions	Reflect on leadership and teamwork examples, write and refine STAR stories
Day 37	Behavioral Questions	Problem-solving and conflict resolution examples, articulate responses clearly
Day 38	Review	Review all topics from Weeks 3-4, reattempt difficult problems, summary notes
Day 39	Review	Review all topics from Weeks 3-4, reattempt difficult problems, summary notes
Day 40	Advanced Dynamic Programming	Longest Increasing Subsequence, Edit Distance, Interleaving String, Wildcard Matching
Day 41	Advanced Dynamic Programming	Decode Ways, Longest Palindromic Subsequence, Burst Balloons, Russian Doll Envelopes
Day 42	Advanced Graph Algorithms	Minimum Spanning Tree, All-Pairs Shortest Path, Bellman-Ford, Floyd-Warshall
Day 43	Advanced Graph Algorithms	Path with Maximum Probability, Network Delay Time, Word Ladder II, Redundant Connection II
Day 44	Miscellaneous Topics	Bit manipulation problems, combinatorics, interval problems
Day 45	Miscellaneous Topics	Review graph and dynamic programming problems, solve any missed or skipped problems
Day 46	System Design Complex	Design Facebook, Design Instagram, focus on database scaling, sharding
Day 47	System Design Complex	Design a Cache System, Design a Rate Limiter, focus on memory management, concurrency
Day 48	System Design Complex	Design an E-commerce Platform, Design Google Drive, focus on file storage, replication
Day 49	Mock System Design Interviews	Conduct mock interviews with peers, review feedback
Day 50	Mock System Design Interviews	Conduct mock interviews with peers, review feedback
Day 51	Coding Mock Interviews	Schedule coding mock interviews, review performance, iterate
Day 52	Coding Mock Interviews	Schedule coding mock interviews, review performance, iterate
Day 53	Coding Mock Interviews	Schedule coding mock interviews, review performance, iterate
Day 54	Review Core Concepts	Review data structures, algorithms, and system design, focus on weak areas
Day 55	Review Core Concepts	Review data structures, algorithms, and system design, focus on weak areas
Day 56	Review Core Concepts	Review data structures, algorithms, and system design, focus on weak areas
Day 57	Review Core Concepts	Review data structures, algorithms, and system design, focus on weak areas
Day 58	Advanced System Design	Design YouTube, Design Google Maps, focus on scalability, user load, real-time processing
Day 59	Advanced System Design	Design a Messaging System, Design a Search Engine, focus on indexing, query optimization
Day 60	Advanced System Design	Review all previously designed systems, address any gaps or weaknesses
Day 61	Advanced System Design	Deep dive into specific components like databases, caching mechanisms, load balancers
Day 62	Advanced System Design	Practice designing complex, large-scale systems, prepare detailed notes
Day 63	Mock System Design Interviews	Conduct final round of mock interviews, focus on presentation and articulation
Day 64	Mock System Design Interviews	Conduct final round of mock interviews, focus on presentation and articulation
Day 65	Behavioral Questions	Review and refine STAR stories, ensure readiness for behavioral questions
Day 66	Behavioral Questions	Reflect on past experiences, prepare additional examples for various scenarios
Day 67	Behavioral Questions	Conduct mock behavioral interviews with peers, iterate based on feedback
Day 68	Final Review	Review all core concepts, key problems, system designs, behavioral questions
Day 69	Final Review	Relax, light review, ensure all materials and notes are organized
Day 70	Final Review	Relax, light review, ensure all materials and notes are organized
Day 71	Final Review	Relax, light review, ensure all materials and notes are organized
Day 72	Coding Mock Interviews	Conduct coding mock interviews, review feedback, iterate
Day 73	Coding Mock Interviews	Conduct coding mock interviews, review feedback, iterate
Day 74	Coding Mock Interviews	Conduct coding mock interviews, review feedback, iterate
Day 75	Coding Mock Interviews	Conduct coding mock interviews, review feedback, iterate
Day 76	Mock System Design Interviews	Conduct system design mock interviews, review feedback, iterate
Day 77	Mock System Design Interviews	Conduct system design mock interviews, review feedback, iterate
Day 78	Mock System Design Interviews	Conduct system design mock interviews, review feedback, iterate
Day 79	Review Core Concepts	Revisit key topics, practice problems, focus on areas of improvement
Day 80	Review Core Concepts	Revisit key topics, practice problems, focus on areas of improvement
Day 81	Review Core Concepts	Revisit key topics, practice problems, focus on areas of improvement
Day 82	Review Core Concepts	Revisit key topics, practice problems, focus on areas of improvement
Day 83	Review Core Concepts	Revisit key topics, practice problems, focus on areas of improvement
Day 84	Review Core Concepts	Revisit key topics, practice problems, focus on areas of improvement
Day 85	Relaxation and Light Review	Light review sessions, rest and stress management
Day 86	Relaxation and Light Review	Light review sessions, rest and stress management
Day 87	Relaxation and Light Review	Light review sessions, rest and stress management
Day 88	Relaxation and Light Review	Light review sessions, rest and stress management
Day 89	Relaxation and Light Review	Light review sessions, rest and stress management
Day 90	Relaxation and Light Review	Light review sessions, rest and stress management