CodeSignal OAs full stack engineer interviews cover both frontend and backend topics including API design, database modelling, React or Vue components, and end-to-end system design.
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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 problemYou 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
Medium
Verified Question
#5
5. OA[CodeSignal] Find Effective Communication Channels
Category: String coding problemYou are given billing records, communication logs, and payment records for a healthcare system. Your task is to determine which communication channel...Input: String
Output: Computed result
coding
Hard
Verified Question
#6
6. 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: ArrayOutput: Array
coding
Hard
Verified Question
#7
7. 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: ArrayOutput: Computed result
coding
Hard
Verified Question
#8
8. OA [CodeSignal] Count Palindrome Paths in Tree
Category: Tree coding problemGiven 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: ListOutput: Computed result
coding
Medium
Verified Question
#9
9. OA [CodeSignal] Final Prices After Discount
Category: Array coding problemYou are given an array
prices where prices[i] is the price of an item. For each item at index i, find the first item at index j > i such that...Input: ArrayOutput: Computed result
coding
Medium
Verified Question
#10
10. OA [CodeSignal] Jump Game
Category: Array coding problemYou are at position
i in an array. From each position, you can jump to: - i + 1 (one step forward) - Any position i + k where k ends in digit...Input: ArrayOutput: Computed result
coding
Medium
Verified Question
#11
11. OA [CodeSignal] Longest Subsequence With Limited Sum
Category: Array coding problemYou are given two arrays:
nums (containing positive integers) and queries (each containing a target sum). For each query, return the maximum...Input: ArrayOutput:** Computed result
coding
Hard
Verified Question
#12
12. OA [CodeSignal] Max Throughput With Budget
Category: Algorithm coding problemYou 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: ListOutput: Integer
coding
Hard
Verified Question
#13
13. OA [CodeSignal] Minimum Edge Reversal Root
Category: Graph coding problemGiven 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
Medium
Verified Question
#14
14. OA [CodeSignal] Minimum Operation To Reduce n To 0
Category: Algorithm coding problemGiven a positive integer
n, in one operation you may replace n with either: - n = n + 2^i, or - n = n - 2^i for any integer i >= 0. Find...Input: Integer(s)Output: Integer
coding
Hard
Verified Question
#15
15. OA [CodeSignal] Purchase Optimization
Category: Array coding problemAlex 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: ArrayOutput: Integer
coding
Medium
Verified Question
#16
16. OA [CodeSignal] Shortest Good Subarray
Category: Array coding problemGiven an array
arr and an integer k, a subarray is called good if it contains at least k distinct integers. Return the length of the...Input: ArrayOutput: Integer
coding
Hard
Verified Question
#17
17. OA [CodeSignal] Touring the Building
Category: Algorithm coding problemYou 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 inputOutput: Computed result
coding
Medium
Verified Question
#18
18. [CodeSignal] Maximum Zero-Sum Triplets
Category: Array coding problem# Question You are given an array
A of integers. A triplet is a sequence of three consecutive elements. A triplet is called zero-sum if the...Input: ArrayOutput: Computed result
coding
Easy
Verified Question
#19
19. [CodeSignal] Coin Table Game
Category: String coding problem# Question A player is playing a game in which coins are placed on and removed from a table. The game consists of multiple rounds. At the beginning...Input: String
Output: Computed result
coding
Easy
Verified Question
#20
20. [CodeSignal] Count Non-Dominant Elements
Category: Array coding problem# Question Given an array of integers
numbers, count all elements that are not equal to numbers[0] or numbers[1] (if those indices exist in the...Input: Array of integersOutput: Computed result
coding
Easy
Verified Question
#21
21. [CodeSignal] Sort Words By Vowel Consonant Difference
Category: Array coding problem# Question You are given a string
text consisting of unique lowercase English words separated by spaces. For each word, compute the absolute...Input: ArrayOutput:** Computed result
coding
Medium
Verified Question
#22
22. [CodeSignal] Warehouse Robot Commands
Category: Matrix coding problem# Question In a highly automated warehouse, a robot organizes packages stored in a rectangular grid. The grid is represented as a 2D list of integers...Input: Matrix (2D array)
Output: Computed result
coding
Hard
Verified Question
#23
23. [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
#24
24. [CodeSignal] Warehouse Emergency Deliveries
Category: Array coding problemAmazon has opened a new warehouse recently. There are no products in the warehouse currently. The warehouse is under inspection for
n days. The...Input: ArrayOutput: Integer
coding
Hard
Verified Question
#25
25. [CodeSignal] Permutation Sorter
Category: Combinatorics coding problemAmazon 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
#26
26. [CodeSignal] Maximum Product Rating
Category: Array coding problemThe 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: ArrayOutput: Computed result
coding
Medium
Verified Question
#27
27. [CodeSignal] Drone Hub Travel
Category: Array coding problemAmazon is expanding its next-generation drone delivery network, consisting of
m hubs arranged in a circular ring (Hub 1 is adjacent to Hub m)....Input: ArrayOutput: Computed result
coding
Medium
Verified Question
#28
28. [CodeSignal] Minimum Security Groups
Category: Array coding problemA financial services company has requested AWS for a private deployment of its cloud network. There are
n servers in the network where the security...Input: ArrayOutput: Integer
coding
Medium
Verified Question
#29
29. [CodeSignal] Maximum Secure Deliveries
Category: Array coding problemYou are given an array
deliveryLogs of size n, where each element represents the number of parts delivered in the i-th log. You are also given...Input: ArrayOutput: Integer
coding
Medium
Verified Question
#30
30. Service Log Aggregator
Category: Trie-based coding problemA distributed system emits log entries from multiple services and worker threads. Each log entry is a colon-separated string in the format...Input: Array
Output: Computed result
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