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 Week 2 — Core Data Structures Week 3 — Trees, Graphs & DP Week 4 — Review & Mock Interviews

Week 1 — Foundations

Arrays, strings, and the patterns that crack 40% of Easy questions.

TIP

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	Focus
Mon – Tue	Sliding Window Two Pointers	5 Easy / Medium problems total
Wed – Thu	Prefix Sum Hash Map	5 problems — aim for pattern recognition, not speed
Fri – Sat	Binary Search	5 problems — master the 4 binary search templates
Sun	Rest & Review	Review: redo any problem you rated hard without notes

Weekly target: 15 problems

Week 2 — Core Data Structures

Stacks, heaps, and linked lists — the backbone of Medium-difficulty interviews.

TIP

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	Focus
Mon – Tue	Stack Monotonic Stack	6 problems — valid parentheses, daily temperatures, histogram
Wed	Heap / Priority Queue	4 problems — kth largest, merge k lists, task scheduler
Thu – Fri	Linked List	6 problems — reversal, cycle detection, merge, nth from end
Sat	Queue / BFS	4 problems — level order, rotting oranges, shortest path
Sun	Rest & Review	Company filter: run through 5 problems from your target company

Weekly target: 20 problems

Week 3 — Trees, Graphs & DP

The hardest week. Slow down on DP — correctness beats speed.

TIP

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	Focus
Mon – Tue	Trees / DFS	7 problems — invert, depth, BST, LCA, path sum, right view
Wed	Graphs	4 problems — islands, clone, components, pacific atlantic
Thu – Fri	Dynamic Programming	6 problems 1D first: climb stairs, house robber, coin change, LIS
Sat	Dynamic Programming	3 problems 2D: LCS, edit distance, unique paths
Sun	Rest & Review	Review the hardest 3 problems from this week, back-of-envelope complexity

Weekly target: 20 problems

Week 4 — Review & Mock Interviews

Polish, speed, and communication — the final mile.

TIP

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	Focus
Mon	Rest & Review	Revisit every problem you marked as Hard — can you solve it in 20 min now?
Tue – Wed	Backtracking Trie Union-Find	5 gap-fill problems across remaining patterns
Thu	Rest & Review	Mock interview 1 — set a 45 min timer, pick 2 random Medium problems
Fri	Rest & Review	Mock interview 2 — focus on communication and edge cases
Sat	Rest & Review	5 random problems without pattern hints — simulate real interview
Sun	Rest & Review	Rest. Review your notes. You are ready.

Weekly target: 10 problems

Must-Know Problems

High-frequency problems that appear most often in interviews. Solve these before anything else.

All problems →

#	Problem	Pattern	Difficulty
01	Longest Substring Without Repeating Characters	Sliding Window	Medium
02	Minimum Window Substring	Sliding Window	Hard
03	Two Sum II - Input Array Is Sorted	Two Pointers	Medium
04	3Sum	Two Pointers	Medium
05	Container With Most Water	Two Pointers	Medium
06	Trapping Rain Water	Two Pointers	Hard
07	Valid Palindrome	Two Pointers	Easy
08	Remove Duplicates from Sorted Array	Two Pointers	Easy
09	Binary Search	Binary Search	Easy
10	Search in Rotated Sorted Array	Binary Search	Medium
11	Find Minimum in Rotated Sorted Array	Binary Search	Medium
12	Subarray Sum Equals K	Prefix Sum	Medium
13	Product of Array Except Self	Prefix Sum	Medium
14	Two Sum	Hash Map	Easy
15	Group Anagrams	Hash Map	Medium
16	Top K Frequent Elements	Hash Map	Medium
17	Valid Anagram	Hash Map	Easy
18	Longest Consecutive Sequence	Hash Map	Medium
19	Valid Parentheses	Stack	Easy
20	Min Stack	Stack	Medium

Ready to start?

Open Week 1 — Sliding Window is the best first pattern to lock in.

Start with Sliding Window Cheat sheets