CodeSignal OAs logo

CodeSignal OAs Hard Interview Questions

22 hard-level practice questions for CodeSignal OAs technical interviews

coding Hard Verified Question #1

1. OA[CodeSignal] Cloud File Storage System


Category: Graph coding problem
# Question Your task is to implement a simple in-memory cloud storage system that maps objects (files) to their metadata (name, size, etc.). You...
Input: Graph (nodes and edges)
Output: Array
coding Hard Verified Question #2

2. OA[CodeSignal] Design Banking System


Category: Graph coding problem
# Question Design a banking system that supports account management, transactions, and various financial operations.
Input: Graph (nodes and edges)
Output: Computed result
coding Hard Verified Question #3

3. OA[CodeSignal] In-Memory Database


Category: Graph coding problem
# Description Implement a simplified in-memory database that supports record manipulation with various operations. The system should handle basic...
Input: Graph (nodes and edges)
Output: Array
coding Hard Verified Question #4

4. OA[CodeSignal] Employee Management System


Category: Graph coding problem
You are tasked with designing an employee management system that tracks work sessions, calculates work hours, handles promotions, and manages salary...
Input: Graph (nodes and edges)
Output: Computed result
coding Hard Verified Question #5

5. OA [CodeSignal] Adventure Levels


Category: Array coding problem
# OA [CodeSignal] Adventure Levels You start with initial energy K. You need to clear a series of adventure levels. For each level i: -...
Input: Array
Output: Array
coding Hard Verified Question #6

6. OA [CodeSignal] Balanced Numbers in Permutation


Category: Array coding problem
# OA [CodeSignal] Balanced Numbers in Permutation Given a permutation p of integers from 1 to n. A number k (where 1 <= k <= n) is called...
Input: Array
Output: Computed result
coding Hard Verified Question #7

7. OA [CodeSignal] Count Palindrome Paths in Tree


Category: Tree coding problem
Given a tree with n nodes where each node has a lowercase English character c[i]. A path is palindromic if the characters along the path can...
Input: List
Output: Computed result
coding Hard Verified Question #8

8. OA [CodeSignal] Max Throughput With Budget


Category: Algorithm coding problem
You have a pipeline of services. Each service has: - Current throughput throughput[i] - Cost to scale up by 1 unit scalecost[i] You have a fixed...
Input: List
Output: Integer
coding Hard Verified Question #9

9. OA [CodeSignal] Minimum Edge Reversal Root


Category: Graph coding problem
Given a directed graph (represented as a tree with directed edges), choose a root node such that the minimum number of edges must be reversed so that...
Input: Graph (nodes and edges)
Output: Integer
coding Hard Verified Question #10

10. OA [CodeSignal] Purchase Optimization


Category: Array coding problem
Alex is shopping at Ozone Gallerie Mall where cubicles are arranged in non-decreasing order of prices from left to right. Given: - prices: array of...
Input: Array
Output: Integer
coding Hard Verified Question #11

11. OA [CodeSignal] Touring the Building


Category: Algorithm coding problem
You are on floor 0 of a building and need to reach floor n. You can use either the lift or stairs. Lift: - Takes t1 time per floor -...
Input: Given input
Output: Computed result
coding Hard Verified Question #12

12. [CodeSignal] House Segments After Destruction


Category: Array coding problem
# Question You are monitoring the building density in a district of houses. The district is represented as a number line, where each house is located...
Input: Array of integers
Output: Array
coding Hard Verified Question #13

13. [CodeSignal] Warehouse Emergency Deliveries


Category: Array coding problem
Amazon has opened a new warehouse recently. There are no products in the warehouse currently. The warehouse is under inspection for n days. The...
Input: Array
Output: Integer
coding Hard Verified Question #14

14. [CodeSignal] Permutation Sorter


Category: Combinatorics coding problem
Amazon engineers are testing a new tool, the Permutation Sorter, built to reorder sequences using limited operations. Given a permutation of...
Input: Integer(s)
Output: Integer
coding Hard Verified Question #15

15. [CodeSignal] Maximum Product Rating


Category: Array coding problem
The engineers at Amazon are working on a new rating system for their products. For each product, an array customer_rating is maintained for the...
Input: Array
Output: Computed result
coding Hard Verified Question #16

16. OA [CodeSignal] Knowledge Base System


Category: Graph coding problem
Design and implement a personal knowledge base called KnowledgeBaseSystem that stores articles with CRUD operations. The system operates entirely...
Input: Graph (nodes and edges)
Output: Computed result
coding Hard Verified Question #17

17. [CodeSignal] Synchronized Pipeline Delays


Category: Binary tree coding problem
A hierarchical data pipeline consists of n broadcast stages, numbered 1 to n, arranged in a perfect binary tree rooted at stage 0. Each stage...
Input: Binary tree
Output: Computed result
coding Hard Verified Question #18

18. [CodeSignal] Fibonacci Storage System


Category: Graph coding problem
A research facility stores artifacts in underground vaults. Each vault has multiple tiers, indexed from 0 (deepest) upward. The capacity of each tier...
Input: Graph (nodes and edges)
Output: Computed result
coding Hard Verified Question #19

19. [CodeSignal] Fixed Price Purchase Optimizer


Category: Algorithm coding problem
A procurement team must purchase n identical components one at a time. For each component, the quoted market price is drawn independently and...
Input: Given input
Output: Integer
coding Hard Verified Question #20

20. [CodeSignal] Battery Rotation Scheduler


Category: Array coding problem
A remote system uses a circular array of backup generators to sustain a critical task. Each generator can power the system for a fixed number of...
Input: Array
Output: Integer
coding Hard Verified Question #21

21. [CodeSignal] Grid Arithmetic Path


Category: Matrix coding problem
You are given a grid where each cell contains either a single digit ('0' to '9') or an arithmetic operator ('+' or '-'). Starting from any cell, you...
Input: Matrix (2D array)
Output: Integer
coding Hard Verified Question #22

22. [CodeSignal] Round-Robin Package Dispatcher


Category: Trie-based coding problem
A logistics platform assigns packages to processing stations in round-robin order. You are given stationCapacity (max packages each station can...
Input: Given input
Output: Integer

No AI generated questions yet for CodeSignal OAs.

Start practicing CodeSignal OAs questions

Sign up for free to access walkthroughs, AI-generated questions, and more.

Get Started Free