75 PROBLEMS · 16 PATTERNS

MASTER
BLIND 75.

Understand the pattern. Prove you can solve it again tomorrow.

Find a problem ↗Today · one idea, one recall check
02OPEN · 3 PROBLEMSTwo pointers0% legacy recall estimate↗03OPEN · 3 PROBLEMSSliding window0/3 recalled↗07OPEN · 11 PROBLEMSTrees & recursive traversal0/11 recalled↗11OPEN · 7 PROBLEMSGraphs: traversal & ordering0/7 recalled↗12OPEN · 13 PROBLEMSDynamic programming0/13 recalled↗
PATTERN ATLAS / VOLUME 01
GUIDED RECALL00/75Practice checks, not verified code mastery.
01Find the pattern

Choose a problem from the complete list.

02Explain the reason

Understand the state, move, and common failure.

03Return and solve

Test your reasoning on a fresh attempt.

YOUR NEXT MOVE

Begin with one exact question.

Start at the first problem. Name what the solution must remember before choosing the tool.

FIND YOUR NEXT PROBLEM

All 75, one clear list.

Open any lesson. 12 have interactive code studios; the remaining lessons currently offer guided reasoning and an external coding handoff.

75 OF 75
01Contains DuplicateArray scans & hashing · Interactive trace + code studioExplore ↗02Valid AnagramArray scans & hashing · Interactive trace + code studioExplore ↗03Two SumArray scans & hashing · Interactive trace + code studioExplore ↗04Group AnagramsArray scans & hashing · Guided lessonExplore ↗05Product of Array Except SelfArray scans & hashing · Guided lessonExplore ↗06Encode and Decode StringsArray scans & hashing · Guided lessonExplore ↗07Longest Consecutive SequenceArray scans & hashing · Guided lessonExplore ↗08Valid PalindromeTwo pointers · Interactive trace + code studioExplore ↗09Container With Most WaterTwo pointers · Interactive trace + code studioExplore ↗103SumTwo pointers · Interactive trace + code studioExplore ↗11Longest Substring Without Repeating CharactersSliding window · Guided lessonExplore ↗12Longest Repeating Character ReplacementSliding window · Guided lessonExplore ↗13Minimum Window SubstringSliding window · Guided lessonExplore ↗14Valid ParenthesesStacks · Guided lessonExplore ↗15Find Minimum in Rotated Sorted ArrayBinary search · Guided lessonExplore ↗16Search in Rotated Sorted ArrayBinary search · Guided lessonExplore ↗17Reverse Linked ListLinked-list rewiring · Interactive trace + code studioExplore ↗18Merge Two Sorted ListsLinked-list rewiring · Guided lessonExplore ↗19Reorder ListLinked-list rewiring · Guided lessonExplore ↗20Remove Nth Node From End of ListLinked-list rewiring · Guided lessonExplore ↗21Linked List CycleLinked-list rewiring · Guided lessonExplore ↗22Invert Binary TreeTrees & recursive traversal · Guided lessonExplore ↗23Maximum Depth of Binary TreeTrees & recursive traversal · Guided lessonExplore ↗24Same TreeTrees & recursive traversal · Guided lessonExplore ↗25Subtree of Another TreeTrees & recursive traversal · Guided lessonExplore ↗26Lowest Common Ancestor of a Binary Search TreeTrees & recursive traversal · Guided lessonExplore ↗27Binary Tree Level Order TraversalTrees & recursive traversal · Guided lessonExplore ↗28Validate Binary Search TreeTrees & recursive traversal · Guided lessonExplore ↗29Kth Smallest Element in a BSTTrees & recursive traversal · Guided lessonExplore ↗30Construct Binary Tree from Preorder and Inorder TraversalTrees & recursive traversal · Guided lessonExplore ↗31Binary Tree Maximum Path SumTrees & recursive traversal · Guided lessonExplore ↗32Serialize and Deserialize Binary TreeTrees & recursive traversal · Guided lessonExplore ↗33Top K Frequent ElementsHeaps & ordered selection · Guided lessonExplore ↗34Merge K Sorted ListsHeaps & ordered selection · Guided lessonExplore ↗35Find Median from Data StreamHeaps & ordered selection · Guided lessonExplore ↗36Word SearchBacktracking · Guided lessonExplore ↗37Implement Trie (Prefix Tree)Tries & prefix search · Guided lessonExplore ↗38Design Add and Search Words Data StructureTries & prefix search · Guided lessonExplore ↗39Word Search IITries & prefix search · Guided lessonExplore ↗40Number of IslandsGraphs: traversal & ordering · Interactive trace + code studioExplore ↗41Clone GraphGraphs: traversal & ordering · Guided lessonExplore ↗42Pacific Atlantic Water FlowGraphs: traversal & ordering · Guided lessonExplore ↗43Course ScheduleGraphs: traversal & ordering · Guided lessonExplore ↗44Number of Connected Components in an Undirected GraphGraphs: traversal & ordering · Guided lessonExplore ↗45Graph Valid TreeGraphs: traversal & ordering · Guided lessonExplore ↗46Alien DictionaryGraphs: traversal & ordering · Guided lessonExplore ↗47Climbing StairsDynamic programming · Interactive trace + code studioExplore ↗48House RobberDynamic programming · Guided lessonExplore ↗49House Robber IIDynamic programming · Guided lessonExplore ↗50Longest Palindromic SubstringDynamic programming · Guided lessonExplore ↗51Palindromic SubstringsDynamic programming · Guided lessonExplore ↗52Decode WaysDynamic programming · Guided lessonExplore ↗53Coin ChangeDynamic programming · Guided lessonExplore ↗54Maximum Product SubarrayDynamic programming · Guided lessonExplore ↗55Word BreakDynamic programming · Guided lessonExplore ↗56Longest Increasing SubsequenceDynamic programming · Guided lessonExplore ↗57Unique PathsDynamic programming · Guided lessonExplore ↗58Longest Common SubsequenceDynamic programming · Guided lessonExplore ↗59Combination Sum IVDynamic programming · Guided lessonExplore ↗60Best Time to Buy and Sell StockGreedy scans · Interactive trace + code studioExplore ↗61Maximum SubarrayGreedy scans · Interactive trace + code studioExplore ↗62Jump GameGreedy scans · Interactive trace + code studioExplore ↗63Insert IntervalIntervals & sweep line · Guided lessonExplore ↗64Merge IntervalsIntervals & sweep line · Guided lessonExplore ↗65Non-overlapping IntervalsIntervals & sweep line · Guided lessonExplore ↗66Meeting RoomsIntervals & sweep line · Guided lessonExplore ↗67Meeting Rooms IIIntervals & sweep line · Guided lessonExplore ↗68Rotate ImageMatrix traversal & transforms · Guided lessonExplore ↗69Spiral MatrixMatrix traversal & transforms · Guided lessonExplore ↗70Set Matrix ZeroesMatrix traversal & transforms · Guided lessonExplore ↗71Number of 1 BitsBit manipulation · Guided lessonExplore ↗72Counting BitsBit manipulation · Guided lessonExplore ↗73Reverse BitsBit manipulation · Guided lessonExplore ↗74Missing NumberBit manipulation · Guided lessonExplore ↗75Sum of Two IntegersBit manipulation · Guided lessonExplore ↗
Browse the curriculum by pattern16 open chapters+
A FOCUSED STUDY GUIDE

What is the Blind 75?

The Blind 75 is a curated set of 75 data structures and algorithms problems that covers the recurring patterns behind coding interviews. It is valuable because it compresses a huge subject into a focused core: arrays, graphs, trees, dynamic programming, linked lists, intervals, heaps, tries, and more.

Blind 75 Master Key organizes the list by pattern. Use the current guided explanations to learn how to recognize a technique, explain its reasoning and revisit the idea. Interactive coding is available on selected lessons while the full learning sessions are developed.

01

Pattern-first reasoning

Understand the signal that points to a technique before you touch the code.

02

Active recall

Retrieve the idea before seeing choices. Guided recall and independent code evidence are kept distinct.

03

All 75 in one place

Browse every problem, open its pattern chapter, and continue to a coding challenge when ready.

HOW TO USE THE BLIND 75
  1. RecogniseName the pattern and the state the solution must remember.
  2. UnderstandWalk through why the algorithm works and where it can fail.
  3. RecallClose the explanation and reconstruct the approach in your own words.
  4. CodeImplement, test edge cases, and revisit weak patterns on another day.
BLIND 75 FAQ

Questions interview candidates ask

Is Blind 75 enough for coding interviews?+

Blind 75 is a strong technical foundation, but no single list covers every interview. Pair it with timed practice, communication drills, role-specific topics, system design when relevant, and mock interviews.

How long does Blind 75 take?+

A focused plan commonly takes several weeks. Your best pace is the one that leaves enough time to revisit problems from memory; durable recall matters more than rushing through the list.

What order should I solve Blind 75 in?+

Study by pattern rather than at random. Start with core array and pointer techniques, then build toward trees, graphs, heaps, and dynamic programming while mixing in spaced review.

Should I memorise Blind 75 solutions?+

No. Memorise the decision process: the clues, invariant, state, complexity, and edge cases. That knowledge transfers when an interviewer changes the problem.