Problem database last updated: June 20, 2025
14 problems · 4 Easy, 9 Medium, 1 Hard · Ranked #117 of 458
4 Easy
29% · avg 23%
9 Medium
64% · avg 59%
1 Hard
7% · avg 18%
Based on 14 reported problems, BlackRock interviews are easier than average - only 7% Hard compared to 18% across all companies. The majority (64%) 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, BlackRock puts unusual emphasis on shortest-path (14.3% of problems, 28.6x the industry average), union-find (14.3% of problems, 4.8x the industry average), graph (14.3% of problems, 4.8x the industry average). If you're short on time, these are the categories to double down on.
The most common topics are array (64.3%), string (42.9%), dynamic-programming (35.7%), hash-table (28.6%). Problems below are sorted by frequency, the ones at the top are asked most often.
| Problem | Difficulty | Frequency | Topics | |
|---|---|---|---|---|
Happy Number Write an algorithm to determine if a number n is happy. | Easy | Very Likely | hash-tablemathtwo-pointers | Solve |
Valid Parentheses Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. | Easy | Very Likely | stringstack | Solve |
Evaluate Division You are given an array of variable pairs equations and an array of real numbers values, where equations[i] = [Ai, Bi] and values[i] represent the equation Ai /... | Medium | Very Likely | arraystringdepth-first-search | Solve |
Find the Maximum Sum of Node Values There exists an undirected tree with n nodes numbered 0 to n - 1. You are given a 0-indexed 2D integer array edges of length n - 1, where edges[i] = [ui, vi] in... | Hard | Likely | arraydynamic-programminggreedy | Solve |
Pairs of Songs With Total Durations Divisible by 60 You are given a list of songs where the ith song has a duration of time[i] seconds. | Medium | Likely | arrayhash-tablecounting | 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 | Likely | arraydynamic-programming | Solve |
Group Anagrams Given an array of strings strs, group the anagrams together. You can return the answer in any order. | Medium | Likely | arrayhash-tablestring | Solve |
Path with Maximum Probability You are given an undirected weighted graph of n nodes (0-indexed), represented by an edge list where edges[i] = [a, b] is an undirected edge connecting the node... | Medium | Sometimes | arraygraphheap-priority-queue | Solve |
Maximize Greatness of an Array You are given a 0-indexed integer array nums. You are allowed to permute nums into a new array perm of your choosing. | Medium | Sometimes | arraytwo-pointersgreedy | Solve |
Longest Palindromic Substring Given a string s, return the longest palindromic substring in s. | Medium | Sometimes | two-pointersstringdynamic-programming | Solve |
Valid Anagram Given two strings s and t, return true if t is an anagram of s, and false otherwise. | Easy | Sometimes | hash-tablestringsorting | Solve |
Coin Change You are given an integer array coins representing coins of different denominations and an integer amount representing a total amount of money. | Medium | Sometimes | arraydynamic-programmingbreadth-first-search | Solve |
Generate Parentheses Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses. | Medium | Sometimes | stringdynamic-programmingbacktracking | Solve |
Number of Islands Given an m x n 2D binary grid grid which represents a map of '1's (land) and '0's (water), return the number of islands. | Medium | Sometimes | arraydepth-first-searchbreadth-first-search | Solve |
Happy Number
SolveWrite an algorithm to determine if a number n is happy.
Valid Parentheses
SolveGiven a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
Evaluate Division
SolveYou are given an array of variable pairs equations and an array of real numbers values, where equations[i] = [Ai, Bi] and values[i] represent the equation Ai /...
Find the Maximum Sum of Node Values
SolveThere exists an undirected tree with n nodes numbered 0 to n - 1. You are given a 0-indexed 2D integer array edges of length n - 1, where edges[i] = [ui, vi] in...
Pairs of Songs With Total Durations Divisible by 60
SolveYou are given a list of songs where the ith song has a duration of time[i] seconds.
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.
Group Anagrams
SolveGiven an array of strings strs, group the anagrams together. You can return the answer in any order.
Path with Maximum Probability
SolveYou are given an undirected weighted graph of n nodes (0-indexed), represented by an edge list where edges[i] = [a, b] is an undirected edge connecting the node...
Maximize Greatness of an Array
SolveYou are given a 0-indexed integer array nums. You are allowed to permute nums into a new array perm of your choosing.
Longest Palindromic Substring
SolveGiven a string s, return the longest palindromic substring in s.
Valid Anagram
SolveGiven two strings s and t, return true if t is an anagram of s, and false otherwise.
Coin Change
SolveYou are given an integer array coins representing coins of different denominations and an integer amount representing a total amount of money.
Generate Parentheses
SolveGiven n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.
Number of Islands
SolveGiven an m x n 2D binary grid grid which represents a map of '1's (land) and '0's (water), return the number of islands.
Frequency scores are based on crowdsourced interview reports. A higher score means the problem has been reported more often in recent BlackRock interviews.
Very Likely
75-100%
Likely
50-74%
Sometimes
25-49%
Rare
0-24%
BlackRock interviews focus heavily on array, string, dynamic-programming 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. BlackRock 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.
BlackRock has been reported to ask 14 distinct coding problems. The most common topics are array, string, dynamic-programming. 4 are Easy difficulty, 9 are Medium, and 1 are Hard. Problems are sorted by frequency - the ones at the top are asked most often.
Based on 14 reported problems, BlackRock interviews are easier than average - only 7% Hard compared to 18% across all companies. 64% 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, dynamic-programming. Practice solving them under time pressure and explaining your approach out loud. Mock interviews with AI can simulate the real experience.
Simulate a real BlackRock coding interview with an AI interviewer. Get a scorecard with specific feedback on your problem-solving, code quality, and communication.
Simulate a BlackRock interview with AIarrow_forward
