Blackrock Interview Questions
List of Real Interview Questions from Blackrock
117 Questions
Updated 2025
Quant Interview Questions
117 questions
1
What is the square root of 1498?
Analyst Interview
2
Given a list of objects, use the Stream API to group the objects based on the 'place' attribute. Then, convert this logic to equivalent SQL code.
Analyst Interview
3
Explain the assumptions of linear regression.
Analyst Interview
4
Write the algorithm for bubble sort.
Analyst Interview
5
How would you implement a Set data structure?
Analyst Interview
6
Swap two values without using a temporary variable.
Analyst Interview
7
Suppose we have three fair dice and we toss them in order. What is the probability that the outcome is strictly increasing? For example, (1, 3, 5) and (3, 5, 6) are allowed, but (4, 3, 5) is not.
Analyst Interview
8
You are given two buckets: one holds 3 litres and the other holds 5 litres. How would you measure exactly 4 litres using only these two buckets?
Analyst Interview
9
How do you write an infinite loop in a programming language of your choice?
Analyst Interview
10
Given a directed acyclic graph (DAG), find the length of the longest path in the graph.
Summer Analyst Interview
11
What is serialization in Java?
Summer Analyst Interview
12
What is the 'finally' block in Java, and when is it used?
Summer Analyst Interview
13
Given a string, find the length of the longest substring that contains only unique characters.
Summer Analyst Interview
14
Describe the differences between a left outer join and a right outer join in database systems.
Summer Analyst Interview
15
Implement a stack using two queues.
Summer Analyst Interview
16
Explain how you would design a Minesweeper game in Java.
Summer Analyst Interview
17
You are performing a regression of Y on X and observe that the variability of the residuals is unequal across the range of X. What can you infer from this?
Summer Analyst Interview
18
If you have three rolls of a die, and after the first and second rolls you can choose either to accept your current roll or roll again, what is the optimal strategy to maximize your final roll, and what is the expected value of your outcome?
Summer Analyst Interview
19
What is the angle between the hour hand and the minute hand at 12:15 on a standard clock?
Summer Analyst Interview
20
Reverse a string in Java.
Summer Analyst Interview
21
Describe Principal Component Analysis (PCA).
Summer Analyst Interview
22
Write an algorithm that sorts a hashmap.
Software Developer Interview
23
Given a string, determine if it is a palindrome, ignoring any characters that are not alphabetic.
Software Engineer Interview
24
1) Reverse a number: Given an integer input, output its digits in reverse order. For example, input: 9966, output: 6699. 2) Word count in a string: Given a string, return the count of each unique word. For example, input: 'The lovely lady is looking lovely as all lady look lovely' output: The: 1, lovely: 3, lady: 2, is: 1, looking: 1, as: 1, all: 1, look: 1. 3) Swap two numbers without using a temporary variable: Given two numbers, swap their values without using a third variable. For example, input: a = 10, b = 20. Output: a = 20, b = 10.
Software Engineer Interview
25
Solve the intersection of two linked lists from scratch, including implementing the linked list data structure. Start with a brute-force approach and optimize it. Also, explain the difference between arrays and linked lists.
Software Engineer Interview
26
Given a singly linked list, find and return the value of the middle node.
Software Developer Interview
27
1) Find the nth node from the end of a linked list. 2) Find the second largest number in an array.
Software Developer Interview
28
Given a binary search tree (BST) and a target value, write an algorithm to determine if the value exists in the BST.
Software Developer Interview
29
Write an algorithm that returns the Nth number in the Fibonacci sequence.
Software Engineer Interview
30
Write a function that returns the median value from a given list of numbers.
Software Engineer Interview
31
Reverse the nodes of a linked list.
Software Engineer Interview
32
Arrange an array so that all zeros are on one side and all ones are on the other side.
Software Engineer Interview
33
Write a function that reverses a string.
Software Engineer Interview
34
Explain the use of the static keyword in the context of Java. What does it mean when a variable or method is declared static?
Software Developer Interview
35
What is the difference between an interface and an abstract class in Java? How does method overloading differ from method overriding? Can you explain the concept of encapsulation? What is the purpose of the 'final' keyword in Java?
Software Engineer Interview
36
Write the bubble sort algorithm.
Software Engineer Interview
37
Implement an isEqual function to compare two objects and determine if they are equal.
Software Engineer Interview
38
What data structure would you use to build a parking lot, and why?
Software Engineer Interview
39
Sort a stack using only one additional stack and a single variable.
Software Engineer Interview
40
Find the first common ancestor of two given nodes in a tree.
Software Engineer Interview
41
How does a HashMap work internally?
Software Engineer Interview
42
Describe how a HashMap works.
Software Developer Interview
43
1. Reverse a string in place. 2. Write a method that converts a decimal number to binary. 3. What is a Singleton? 4. What are the differences between Array and ArrayList in Java? 5. If you were to design a phone directory, what data structure would you use? 6. Calculate Fibonacci numbers with and without recursion; for example, given an array [3, 5, 4], return the 3rd, 5th, and 4th Fibonacci numbers in an array. What is the complexity of your algorithm? 7. Return the length of the last word in a sentence. For example: String s = "Hello Wang" should return 4; String s2 = "Hello " should return 5; String s3 = "" should return 0. 8. Given a number greater than 9, write a program that repeatedly sums its digits until the result is less than 10 (e.g., 38 → 3+8=11, then 1+1=2, stop). 9. What are the differences between String, StringBuilder, and StringBuffer in Java?
Software Engineer Interview
44
How does a HashMap find an entry, and what is the runtime complexity of that search operation?
Software Engineer Interview
45
Why is multiple inheritance not supported in Java?
Software Engineer Interview
46
Given an array of integers (both positive and negative), find the maximum sum of consecutive integers.
Software Engineer Interview
47
Implement a resizable stack data structure in your preferred programming language.
Software Engineer Interview
48
Write a function that takes a string and an integer as inputs. The integer specifies the maximum number of consecutive repeated letters to allow in the returned string. For example: ('aab', 1) -> 'ab'; ('aaabba', 2) -> 'aabba'.
Software Engineer Interview
49
Write a method to perform binary search on a sorted array.
Software Engineer Interview
50
How do you convert an expression in infix (prefix) notation to postfix notation?
Software Engineer Interview
51
Find the least common ancestor of two given nodes in an N-ary tree.
Software Engineer Interview
52
In Java, how would you create a deck of cards and implement a method to shuffle them?
Software Engineer Interview
53
How do you detect a cycle in a circular linked list?
Software Engineer Interview
54
1. Write an SQL query to find the second largest entry in a table. 2. Reverse the words in a sentence without using another string.
Intern Interview
55
What is the angle between the hour hand and the minute hand of a clock at 3:15?
Intern Interview
56
What is convexity? How is it calculated? What does it tell you?
Intern Interview
57
What is the Black-Scholes option pricing model?
Associate Interview
58
Design a cache system that stores key-value pairs with a fixed capacity. When the cache reaches its limit, it should evict the least recently used (LRU) entry. Implement methods to get a value by key, set a new key-value pair, and delete a specific key from the cache using a data structure of your choice.
Associate Interview
59
Explain valuation techniques for pricing mortgage and corporate bonds.
Associate Interview
60
How do you find the number of words in a file?
Internship Interview
61
1. What are the differences between DDL, DML, and TCL in SQL? 2. How can you find the middle node of a singly linked list in a single pass? 3. How do you design a stack that can return the minimum element at any given time in constant time?
Internship Interview
62
What is linear regression?
Summer Intern Interview
63
How do you detect a cycle in a linked list?
Software Engineer(Internship) Interview
64
You are given 8 identical-looking balls. Seven of the balls are equal in weight, and one of them is lighter. How would you efficiently find the lighter ball?
Software Engineer(Internship) Interview
65
Given a set of returns for a portfolio, calculate the variance of the portfolio.
Summer Internship Interview
66
In the context of linear regression, what are the assumptions that should be checked before applying the model?
Financial Analyst Interview
67
What are convexity and duration, and what is the difference between them?
Financial Analyst Interview
68
Given a binary search tree (BST) and two nodes, find their lowest common ancestor.
Business Analyst Interview
69
Explain the concept of a left inner join.
Business Analyst Interview
70
Write a program to determine if the current configuration of a Tic Tac Toe board allows the 'X' player to win on their next move. A winning configuration is one where three 'X's appear in a row. Your task is to find if there is a row, column, or diagonal with exactly two 'X's and an empty spot, indicating that 'X' can win by playing in that spot. The program should output the coordinate (x, y) of the winning location.
Spring Week Interview
71
What is the duration of a bond? Explain how it is calculated.
PAG Analyst Interview
72
What are duration and convexity?
PAG Analyst Interview
73
Explain the mathematical reasoning behind negative convexity.
PAG Analyst Interview
74
You have two strings and one lighter. How many minutes does it take for a string to disappear when you light both of its ends?
Analyst - Portfolio Analytics Group Interview
75
Write an algorithm that sorts a hashmap.
Software Developer Interview
76
Answer the following programming questions: 1) Reverse a number. For example, input: 9966, output: 6699. 2) Count occurrences of each word in a string. For example, input: "The lovely lady is looking lovely as all lady look lovely", output: The: 1, lovely: 3, lady: 2, is: 1, looking: 1, as: 1, all: 1, look: 1. 3) Swap two numbers without using a temporary variable. For example, input: a = 10, b = 20; output: a = 20, b = 10.
Software Engineer Interview
77
Implement a solution to find the intersection node of two singly linked lists, starting from a brute-force approach to the most optimal solution. Also, implement the linked list data structure from scratch. Additionally, explain the differences between arrays and linked lists.
Software Engineer Interview
78
Given a singly linked list, find and return the middle node of the list. If there are two middle nodes, return the second middle node.
Software Developer Interview
79
1) Find the nth node from the end of a linked list. 2) Find the second largest number in an array.
Software Developer Interview
80
What is object-oriented programming (OOP)? What is the difference between arrays and lists? How do you reverse an array?
Software Engineer Interview
81
Given a binary search tree (BST) and a target value, find whether the element exists in the BST.
Software Developer Interview
82
Write an algorithm that returns the Nth number in the Fibonacci sequence.
Software Engineer Interview
83
Write a function that returns the median of a list of numbers.
Software Engineer Interview
84
Reverse the nodes of a linked list.
Software Engineer Interview
85
Arrange an array so that all zeros are on one side and all ones are on the other.
Software Engineer Interview
86
Write a function that reverses a string.
Software Engineer Interview
87
Explain the keyword 'static' in the context of Java. What is its purpose and how is it used?
Software Developer Interview
88
What is the difference between an interface and an abstract class in Java? How does method overloading differ from method overriding? Can you explain the concept of encapsulation? What is the purpose of the 'final' keyword in Java?
Software Engineer Interview
89
Write the bubble sort algorithm.
Software Engineer Interview
90
Implement an isEqual function to compare two objects and determine if they are equal.
Software Engineer Interview
91
What data structure would you use to build a parking lot, and why?
Software Engineer Interview
92
Sort a stack using only one other stack and a single variable.
Software Engineer Interview
93
Given a tree and two specified nodes, find their first common ancestor.
Software Engineer Interview
94
How does a HashMap work internally?
Software Engineer Interview
95
Describe how a HashMap works.
Software Developer Interview
96
1. Reverse a string in place. 2. Write a method to convert a decimal number to binary. 3. What is the Singleton pattern? 4. What are the differences between Array and ArrayList in Java? 5. If you are going to design a phone directory, what data structure would you use? 6. Calculate Fibonacci numbers with and without recursion. For example, given an array [3, 5, 4], return the 3rd, 5th, and 4th Fibonacci numbers and store them in an array. What is the complexity of your algorithm? 7. Return the length of the last word in a sentence. For example: String s = 'Hello Wang' should return 4; String s2 = 'Hello ' should return 5; String s3 = '' should return 0. 8. Given an input number greater than 9, write a program that repeatedly sums all its digits until the sum is less than 10. For example, given 38: 3+8=11, 1+1=2, stop. 9. What are the differences between String, StringBuilder, and StringBuffer in Java?
Software Engineer Interview
97
Why is multiple inheritance not supported in Java?
Software Engineer Interview
98
Given an array of integers (both positive and negative), find the maximum sum of any consecutive subarray.
Software Engineer Interview
99
How does a HashMap find an entry, and what is the runtime of that search?
Software Engineer Interview
100
Implement a stack data structure that dynamically resizes its storage as elements are pushed and popped.
Software Engineer Interview
101
Write a function that takes in a string and an integer n. The integer determines the maximum number of allowed repeated consecutive letters. For example, ('aab', 1) should return 'ab'. ('aaabba', 2) should return 'aabba'.
Software Engineer Interview
102
Write a method that implements binary search.
Software Engineer Interview
103
How do you convert an expression in infix (or prefix) notation to postfix notation?
Software Engineer Interview
104
Find the least common ancestor of two nodes in an N-ary tree.
Software Engineer Interview
105
In Java, how would you create a deck of cards and implement a method to shuffle them?
Software Engineer Interview
106
Derive the Ordinary Least Squares (OLS) estimator and discuss its bias.
Quantitative Analyst Interview
107
How can you measure the extent to which the price of a security fluctuates?
Quantitative Analyst Interview
108
What are covariance and variance? Define each and explain their differences.
Quantitative Analyst Interview
109
How would you sort an array of numbers efficiently?
Quantitative Analyst Interview
110
What are SQL correlated queries? Provide a definition and give an example.
Quantitative Analyst Interview
111
Explain duration and its effect on bonds and bond valuations.
Portfolio Analyst Interview
112
What is the square of 72?
Aladdin Client Services Interview
113
Write Python code to access specific data from Excel and CSV files.
Graduate Analyst Interview
114
How can you join two database tables in SQL without using the JOIN keyword?
Software Engineer Intern Interview
115
Implement a hashMap data structure. What are the differences between a hashMap and a treeMap?
Software Engineer Intern Interview
116
1. What is the difference between shallow copy and deep copy in C++? 2. Implement a class using the singleton pattern in Java. 3. Find the first common ancestor of two nodes in a binary search tree (BST).
Software Developer Intern Interview
117
What are duration and convexity for bonds? Explain their definitions and how they are used in bond pricing and risk management.
Aladdin Client Service Analyst Interview