Problem database last updated: June 20, 2025
48 problems · 8 Easy, 28 Medium, 12 Hard · Ranked #43 of 458
8 Easy
17% · avg 23%
28 Medium
58% · avg 59%
12 Hard
25% · avg 18%
Based on 48 reported problems, Roblox interviews are slightly harder than average - 25% 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, Roblox puts unusual emphasis on data-stream (4.2% of problems, 6.3x the industry average), ordered-set (4.2% of problems, 4.1x the industry average), counting (10.4% of problems, 3.1x the industry average). If you're short on time, these are the categories to double down on.
The most common topics are array (68.8%), string (33.3%), hash-table (31.3%), matrix (18.8%). Problems below are sorted by frequency, the ones at the top are asked most often.
| Problem | Difficulty | Frequency | Topics | |
|---|---|---|---|---|
Reorganize String Given a string s, rearrange the characters of s so that any two adjacent characters are not the same. | Medium | Very Likely | hash-tablestringgreedy | Solve |
Design Browser History You have a browser of one tab where you start on the homepage and you can visit another url, get back in the history number of steps or move forward in the hist... | Medium | Very Likely | arraylinked-liststack | Solve |
Task Scheduler You are given an array of CPU tasks, each labeled with a letter from A to Z, and a number n. Each CPU interval can be idle or allow the completion of one task.... | Medium | Very Likely | arrayhash-tablegreedy | Solve |
Maximize Distance to Closest Person You are given an array representing a row of seats where seats[i] = 1 represents a person sitting in the ith seat, and seats[i] = 0 represents that the ith seat... | Medium | Very Likely | array | Solve |
Merge Intervals Given an array of intervals where intervals[i] = [starti, endi], merge all overlapping intervals, and return an array of the non-overlapping intervals that cove... | Medium | Very Likely | arraysorting | Solve |
Text Justification Given an array of strings words and a width maxWidth, format the text such that each line has exactly maxWidth characters and is fully (left and right) justifie... | Hard | Likely | arraystringsimulation | Solve |
Magnetic Force Between Two Balls In the universe Earth C-137, Rick discovered a special form of magnetic force between two balls if they are put in his new invented basket. Rick has n empty bas... | Medium | Likely | arraybinary-searchsorting | Solve |
Maximum Number of Occurrences of a Substring Given a string s, return the maximum number of occurrences of any substring under the following rules: | Medium | Likely | hash-tablestringsliding-window | Solve |
Convert Binary Number in a Linked List to Integer Given head which is a reference node to a singly-linked list. The value of each node in the linked list is either 0 or 1. The linked list holds the binary repre... | Easy | Likely | linked-listmath | Solve |
Students and Examinations Table: Students | Easy | Likely | database | Solve |
Subdomain Visit Count A website domain "discuss.leetcode.com" consists of various subdomains. At the top level, we have "com", at the next level, we have "leetcode.com" and at the lo... | Medium | Likely | arrayhash-tablestring | Solve |
Group the People Given the Group Size They Belong To There are n people that are split into some unknown number of groups. Each person is labeled with a unique ID from 0 to n - 1. | Medium | Likely | arrayhash-tablegreedy | Solve |
Count Number of Nice Subarrays Given an array of integers nums and an integer k. A continuous subarray is called nice if there are k odd numbers on it. | Medium | Likely | arrayhash-tablemath | Solve |
Integer to English Words Convert a non-negative integer num to its English words representation. | Hard | Likely | mathstringrecursion | Solve |
Valid Parentheses Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. | Easy | Likely | stringstack | 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 |
Rotate Image You are given an n x n 2D matrix representing an image, rotate the image by 90 degrees (clockwise). | Medium | Likely | arraymathmatrix | Solve |
Number of Flowers in Full Bloom You are given a 0-indexed 2D integer array flowers, where flowers[i] = [starti, endi] means the ith flower will be in full bloom from starti to endi (inclusive)... | Hard | Likely | arrayhash-tablebinary-search | Solve |
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 | Likely | arraytwo-pointersmatrix | Solve |
Spiral Matrix Given an m x n matrix, return all elements of the matrix in spiral order. | Medium | Likely | arraymatrixsimulation | Solve |
Trapping Rain Water Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap after raining. | Hard | Likely | arraytwo-pointersdynamic-programming | Solve |
Block Placement Queries There exists an infinite number line, with its origin at 0 and extending towards the positive x-axis. | Hard | Likely | arraybinary-searchbinary-indexed-tree | Solve |
Split Message Based on Limit You are given a string, message, and a positive integer, limit. | Hard | Likely | stringenumeration | Solve |
Largest Rectangle in Histogram Given an array of integers heights representing the histogram's bar height where the width of each bar is 1, return the area of the largest rectangle in the his... | Hard | Sometimes | arraystackmonotonic-stack | Solve |
Longest Common Prefix Write a function to find the longest common prefix string amongst an array of strings. | Easy | Sometimes | arraystringtrie | Solve |
First Missing Positive Given an unsorted integer array nums. Return the smallest positive integer that is not present in nums. | Hard | Sometimes | arrayhash-table | Solve |
Number of Adjacent Elements With the Same Color You are given an integer n representing an array colors of length n where all elements are set to 0's meaning uncolored. You are also given a 2D integer array q... | Medium | Sometimes | array | Solve |
Find the Length of the Longest Common Prefix You are given two arrays with positive integers arr1 and arr2. | Medium | Sometimes | arrayhash-tablestring | Solve |
Subarrays with K Different Integers Given an integer array nums and an integer k, return the number of good subarrays of nums. | Hard | Sometimes | arrayhash-tablesliding-window | Solve |
Minimum Falling Path Sum II Given an n x n integer matrix grid, return the minimum sum of a falling path with non-zero shifts. | Hard | Sometimes | arraydynamic-programmingmatrix | Solve |
Course Schedule There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1. You are given an array prerequisites where prerequisites[i] = [ai, b... | Medium | Sometimes | depth-first-searchbreadth-first-searchgraph | Solve |
Rotting Oranges You are given an m x n grid where each cell can have one of three values: | Medium | Sometimes | arraybreadth-first-searchmatrix | 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 | Sometimes | arraystringbacktracking | Solve |
Number of Recent Calls You have a RecentCounter class which counts the number of recent requests within a certain time frame. | Easy | Sometimes | designqueuedata-stream | Solve |
Spiral Matrix II Given a positive integer n, generate an n x n matrix filled with elements from 1 to n2 in spiral order. | Medium | Sometimes | arraymatrixsimulation | Solve |
Jump Game II You are given a 0-indexed array of integers nums of length n. You are initially positioned at index 0. | Medium | Sometimes | arraydynamic-programminggreedy | Solve |
Basic Calculator IV Given an expression such as expression = "e + 8 - a + 5" and an evaluation map such as {"e": 1} (given in terms of evalvars = ["e"] and evalints = [1]), return... | Hard | Sometimes | hash-tablemathstring | Solve |
Remove Colored Pieces if Both Neighbors are the Same Color There are n pieces arranged in a line, and each piece is colored either by 'A' or by 'B'. You are given a string colors of length n where colors[i] is the color... | Medium | Sometimes | mathstringgreedy | Solve |
Diagonal Traverse Given an m x n matrix mat, return an array of all the elements of the array in a diagonal order. | Medium | Sometimes | arraymatrixsimulation | Solve |
Unique Paths There is a robot on an m x n grid. The robot is initially located at the top-left corner (i.e., grid[0][0]). The robot tries to move to the bottom-right corner... | Medium | Sometimes | mathdynamic-programmingcombinatorics | Solve |
Image Smoother An image smoother is a filter of the size 3 x 3 that can be applied to each cell of an image by rounding down the average of the cell and the eight surrounding... | Easy | Sometimes | arraymatrix | Solve |
Accounts Merge Given a list of accounts where each element accounts[i] is a list of strings, where the first element accounts[i][0] is a name, and the rest of the elements are... | Medium | Sometimes | arrayhash-tablestring | Solve |
Best Time to Buy and Sell Stock You are given an array prices where prices[i] is the price of a given stock on the ith day. | Easy | Sometimes | arraydynamic-programming | Solve |
Longest Substring Without Repeating Characters Given a string s, find the length of the longest substring without duplicate characters. | Medium | Sometimes | hash-tablestringsliding-window | Solve |
Two Sum Given an array of integers nums and an integer target, return the indices of the two numbers that add up to target. | Easy | Sometimes | arrayhash-map | Solve |
Minimum Absolute Difference Between Elements With Constraint You are given a 0-indexed integer array nums and an integer x. | Medium | Sometimes | arraybinary-searchordered-set | Solve |
Longest Consecutive Sequence Given an unsorted array of integers nums, return the length of the longest consecutive elements sequence. | Medium | Sometimes | arrayhash-tableunion-find | Solve |
Minimum Number of Frogs Croaking You are given the string croakOfFrogs, which represents a combination of the string "croak" from different frogs, that is, multiple frogs can croak at the same... | Medium | Sometimes | stringcounting | Solve |
Reorganize String
SolveGiven a string s, rearrange the characters of s so that any two adjacent characters are not the same.
Design Browser History
SolveYou have a browser of one tab where you start on the homepage and you can visit another url, get back in the history number of steps or move forward in the hist...
Task Scheduler
SolveYou are given an array of CPU tasks, each labeled with a letter from A to Z, and a number n. Each CPU interval can be idle or allow the completion of one task....
Maximize Distance to Closest Person
SolveYou are given an array representing a row of seats where seats[i] = 1 represents a person sitting in the ith seat, and seats[i] = 0 represents that the ith seat...
Merge Intervals
SolveGiven an array of intervals where intervals[i] = [starti, endi], merge all overlapping intervals, and return an array of the non-overlapping intervals that cove...
Text Justification
SolveGiven an array of strings words and a width maxWidth, format the text such that each line has exactly maxWidth characters and is fully (left and right) justifie...
Magnetic Force Between Two Balls
SolveIn the universe Earth C-137, Rick discovered a special form of magnetic force between two balls if they are put in his new invented basket. Rick has n empty bas...
Maximum Number of Occurrences of a Substring
SolveGiven a string s, return the maximum number of occurrences of any substring under the following rules:
Convert Binary Number in a Linked List to Integer
SolveGiven head which is a reference node to a singly-linked list. The value of each node in the linked list is either 0 or 1. The linked list holds the binary repre...
Subdomain Visit Count
SolveA website domain "discuss.leetcode.com" consists of various subdomains. At the top level, we have "com", at the next level, we have "leetcode.com" and at the lo...
Group the People Given the Group Size They Belong To
SolveThere are n people that are split into some unknown number of groups. Each person is labeled with a unique ID from 0 to n - 1.
Count Number of Nice Subarrays
SolveGiven an array of integers nums and an integer k. A continuous subarray is called nice if there are k odd numbers on it.
Integer to English Words
SolveConvert a non-negative integer num to its English words representation.
Valid Parentheses
SolveGiven a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
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...
Rotate Image
SolveYou are given an n x n 2D matrix representing an image, rotate the image by 90 degrees (clockwise).
Number of Flowers in Full Bloom
SolveYou are given a 0-indexed 2D integer array flowers, where flowers[i] = [starti, endi] means the ith flower will be in full bloom from starti to endi (inclusive)...
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:
Spiral Matrix
SolveGiven an m x n matrix, return all elements of the matrix in spiral order.
Trapping Rain Water
SolveGiven n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap after raining.
Block Placement Queries
SolveThere exists an infinite number line, with its origin at 0 and extending towards the positive x-axis.
Split Message Based on Limit
SolveYou are given a string, message, and a positive integer, limit.
Largest Rectangle in Histogram
SolveGiven an array of integers heights representing the histogram's bar height where the width of each bar is 1, return the area of the largest rectangle in the his...
Longest Common Prefix
SolveWrite a function to find the longest common prefix string amongst an array of strings.
First Missing Positive
SolveGiven an unsorted integer array nums. Return the smallest positive integer that is not present in nums.
Number of Adjacent Elements With the Same Color
SolveYou are given an integer n representing an array colors of length n where all elements are set to 0's meaning uncolored. You are also given a 2D integer array q...
Find the Length of the Longest Common Prefix
SolveYou are given two arrays with positive integers arr1 and arr2.
Subarrays with K Different Integers
SolveGiven an integer array nums and an integer k, return the number of good subarrays of nums.
Minimum Falling Path Sum II
SolveGiven an n x n integer matrix grid, return the minimum sum of a falling path with non-zero shifts.
Course Schedule
SolveThere are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1. You are given an array prerequisites where prerequisites[i] = [ai, b...
Rotting Oranges
SolveYou are given an m x n grid where each cell can have one of three values:
Word Search II
SolveGiven an m x n board of characters and a list of strings words, return all words on the board.
Number of Recent Calls
SolveYou have a RecentCounter class which counts the number of recent requests within a certain time frame.
Spiral Matrix II
SolveGiven a positive integer n, generate an n x n matrix filled with elements from 1 to n2 in spiral order.
Jump Game II
SolveYou are given a 0-indexed array of integers nums of length n. You are initially positioned at index 0.
Basic Calculator IV
SolveGiven an expression such as expression = "e + 8 - a + 5" and an evaluation map such as {"e": 1} (given in terms of evalvars = ["e"] and evalints = [1]), return...
Remove Colored Pieces if Both Neighbors are the Same Color
SolveThere are n pieces arranged in a line, and each piece is colored either by 'A' or by 'B'. You are given a string colors of length n where colors[i] is the color...
Diagonal Traverse
SolveGiven an m x n matrix mat, return an array of all the elements of the array in a diagonal order.
Unique Paths
SolveThere is a robot on an m x n grid. The robot is initially located at the top-left corner (i.e., grid[0][0]). The robot tries to move to the bottom-right corner...
Image Smoother
SolveAn image smoother is a filter of the size 3 x 3 that can be applied to each cell of an image by rounding down the average of the cell and the eight surrounding...
Accounts Merge
SolveGiven a list of accounts where each element accounts[i] is a list of strings, where the first element accounts[i][0] is a name, and the rest of the elements are...
Best Time to Buy and Sell Stock
SolveYou are given an array prices where prices[i] is the price of a given stock on the ith day.
Longest Substring Without Repeating Characters
SolveGiven a string s, find the length of the longest substring without duplicate characters.
Two Sum
SolveGiven an array of integers nums and an integer target, return the indices of the two numbers that add up to target.
Minimum Absolute Difference Between Elements With Constraint
SolveYou are given a 0-indexed integer array nums and an integer x.
Longest Consecutive Sequence
SolveGiven an unsorted array of integers nums, return the length of the longest consecutive elements sequence.
Minimum Number of Frogs Croaking
SolveYou are given the string croakOfFrogs, which represents a combination of the string "croak" from different frogs, that is, multiple frogs can croak at the same...
Frequency scores are based on crowdsourced interview reports. A higher score means the problem has been reported more often in recent Roblox interviews.
Very Likely
75-100%
Likely
50-74%
Sometimes
25-49%
Rare
0-24%
Roblox 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. Roblox 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.
Roblox has been reported to ask 48 distinct coding problems. The most common topics are array, string, hash-table. 8 are Easy difficulty, 28 are Medium, and 12 are Hard. Problems are sorted by frequency - the ones at the top are asked most often.
Based on 48 reported problems, Roblox interviews are slightly harder than average - 25% 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.
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.
Simulate a real Roblox coding interview with an AI interviewer. Get a scorecard with specific feedback on your problem-solving, code quality, and communication.
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