How often are these problems asked?
Frequency scores are based on crowdsourced interview reports. A higher score means the problem has been reported more often in recent Block interviews.
Very Likely
75-100%
Likely
50-74%
Sometimes
25-49%
Rare
0-24%
Problem database last updated: June 20, 2025
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Block Coding Interview Questions
12 problems · 1 Easy, 7 Medium, 4 Hard · Ranked #129 of 458
Difficulty breakdown
1 Easy
8% · avg 23%
7 Medium
58% · avg 59%
4 Hard
33% · avg 18%
Top topics
array
66.7%
string
41.7%1.5x
hash-table
33.3%1.5x
matrix
25%2.8x
simulation
25%5.8x
design
25%4.3x
Interview profile
Based on 12 reported problems, Block interviews are significantly harder than average - 33% Hard vs 18% across all companies. The majority (58%) of questions are Medium difficulty, which is typical for companies that want to see solid fundamentals without excessive trick questions.
Compared to the industry average, Block puts unusual emphasis on trie (25% of problems, 9.4x the industry average), simulation (25% of problems, 5.8x the industry average), design (25% of problems, 4.3x the industry average). If you're short on time, these are the categories to double down on.
The most common topics are array (66.7%), string (41.7%), hash-table (33.3%), matrix (25%). Problems below are sorted by frequency, the ones at the top are asked most often.
All 12 problems
| Problem | Difficulty | Frequency | Topics | |
|---|---|---|---|---|
Rotating the Box You are given an m x n matrix of characters boxGrid representing a side-view of a box. Each cell of the box is one of the following: | Medium | Very Likely | arraytwo-pointersmatrix | Solve |
Pancake Sorting Given an array of integers arr, sort the array by performing a series of pancake flips. | Medium | Very Likely | arraytwo-pointersgreedy | Solve |
Count Nice Pairs in an Array You are given an array nums that consists of non-negative integers. Let us define rev(x) as the reverse of the non-negative integer x. For example, rev(123) = 3... | Medium | Very Likely | arrayhash-tablemath | Solve |
Available Captures for Rook You are given an 8 x 8 matrix representing a chessboard. There is exactly one white rook represented by 'R', some number of white bishops 'B', and some number o... | Easy | Very Likely | arraymatrixsimulation | Solve |
Walking Robot Simulation II A width x height grid is on an XY-plane with the bottom-left cell at (0, 0) and the top-right cell at (width - 1, height - 1). The grid is aligned with the four... | Medium | Very Likely | designsimulation | Solve |
Word Break Given a string s and a dictionary of strings wordDict, return true if s can be segmented into a space-separated sequence of one or more dictionary words. | Medium | Very Likely | arrayhash-tablestring | Solve |
Number of Black Blocks You are given two integers m and n representing the dimensions of a 0-indexed m x n grid. | Medium | Very Likely | arrayhash-tableenumeration | Solve |
Falling Squares There are several squares being dropped onto the X-axis of a 2D plane. | Hard | Very Likely | arraysegment-treeordered-set | Solve |
Design a Text Editor Design a text editor with a cursor that can do the following: | Hard | Very Likely | linked-liststringstack | Solve |
Implement Trie (Prefix Tree) A trie (pronounced as "try") or prefix tree is a tree data structure used to efficiently store and retrieve keys in a dataset of strings. There are various appl... | Medium | Likely | hash-tablestringdesign | Solve |
Integer to English Words Convert a non-negative integer num to its English words representation. | Hard | Likely | mathstringrecursion | Solve |
Word Search II Given an m x n board of characters and a list of strings words, return all words on the board. | Hard | Likely | arraystringbacktracking | Solve |
Rotating the Box
SolveYou are given an m x n matrix of characters boxGrid representing a side-view of a box. Each cell of the box is one of the following:
MediumVery Likely
arraytwo-pointersmatrix
Pancake Sorting
SolveGiven an array of integers arr, sort the array by performing a series of pancake flips.
MediumVery Likely
arraytwo-pointersgreedy
Count Nice Pairs in an Array
SolveYou are given an array nums that consists of non-negative integers. Let us define rev(x) as the reverse of the non-negative integer x. For example, rev(123) = 3...
MediumVery Likely
arrayhash-tablemath
Available Captures for Rook
SolveYou are given an 8 x 8 matrix representing a chessboard. There is exactly one white rook represented by 'R', some number of white bishops 'B', and some number o...
EasyVery Likely
arraymatrixsimulation
Walking Robot Simulation II
SolveA width x height grid is on an XY-plane with the bottom-left cell at (0, 0) and the top-right cell at (width - 1, height - 1). The grid is aligned with the four...
MediumVery Likely
designsimulation
Word Break
SolveGiven a string s and a dictionary of strings wordDict, return true if s can be segmented into a space-separated sequence of one or more dictionary words.
MediumVery Likely
arrayhash-tablestring
Number of Black Blocks
SolveYou are given two integers m and n representing the dimensions of a 0-indexed m x n grid.
MediumVery Likely
arrayhash-tableenumeration
Falling Squares
SolveThere are several squares being dropped onto the X-axis of a 2D plane.
HardVery Likely
arraysegment-treeordered-set
Design a Text Editor
SolveDesign a text editor with a cursor that can do the following:
HardVery Likely
linked-liststringstack
Implement Trie (Prefix Tree)
SolveA trie (pronounced as "try") or prefix tree is a tree data structure used to efficiently store and retrieve keys in a dataset of strings. There are various appl...
MediumLikely
hash-tablestringdesign
Integer to English Words
SolveConvert a non-negative integer num to its English words representation.
HardLikely
mathstringrecursion
Word Search II
SolveGiven an m x n board of characters and a list of strings words, return all words on the board.
HardLikely
arraystringbacktracking
Preparing for your Block coding interview
Block interviews focus heavily on array, string, hash-table problems. If you're short on time, these are the categories to prioritize. The problems on this page are sorted by frequency, so start from the top and work your way down.
Beyond solving problems, practice explaining your approach. Block interviewers care about your thought process - how you break down a problem, consider edge cases, and evaluate tradeoffs between solutions. A clean O(n) solution you can explain clearly beats an O(log n) solution you can't articulate.
Looking for more companies? Browse all 458 companies in our directory, or sharpen your fundamentals with our free data structure visualizers and AI-powered DSA tutor.
Frequently Asked Questions
What coding problems does Block ask in interviews?add
Block has been reported to ask 12 distinct coding problems. The most common topics are array, string, hash-table. 1 are Easy difficulty, 7 are Medium, and 4 are Hard. Problems are sorted by frequency - the ones at the top are asked most often.
How hard are Block coding interviews?add
Based on 12 reported problems, Block interviews are significantly harder than average - 33% Hard vs 18% across all companies. 58% of questions are Medium difficulty. Focus on the high-frequency Medium problems first, then work through the Hard ones.
How should I prepare for a Block coding interview?add
Start with the highest-frequency problems listed on this page. Focus on the core topics: array, string, hash-table. Practice solving them under time pressure and explaining your approach out loud. Mock interviews with AI can simulate the real experience.
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