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Coding & Algorithms Interview Questions
Practice 9403 coding, system design and machine learning questions from 546 companies, sorted by role, topic and interview round. Every question has step-by-step hints, a code runner that supports 8 languages and an AI mentor; members also get the full solution walkthrough.
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Showing 1351–1380 of 3276 results
- Hudson River TradingMediumData ScientistCount inversions in a permutation
This question evaluates understanding of inversion counting in permutations, testing algorithmic problem-solving, complexity analysis, and data-structure reasoning about pairwise order relations.
Coding & AlgorithmsTechnical Screen - Hudson River TradingEasySoftware EngineerCount players reaching end with moving watchers
This problem tests your ability to model state transitions over discrete time steps and efficiently track interval coverage using sorting and sweep-line logic.
Coding & AlgorithmsTechnical ScreenSimulationGeometryOptimization - Hudson River TradingMediumSoftware EngineerDetermine Whether Two Integers Sum to a Target
This problem tests proficiency with hash sets to achieve linear time complexity and emphasizes defensive programming practices like input validation and immutability.
Coding & AlgorithmsTechnical ScreenHash SetArraysTwo Pointers - Hudson River TradingHardSoftware EngineerFinal Grid Position Under Timestamped Direction Changes With Dot Obstacles
An object on a grid changes direction whenever a timestamped action arrives and moves one cell per time unit until a blocked cell or the grid edge stops it. The task asks for its cell at a given end time, testing precise reading of the rules, including that dot cells are obstacles, and efficient handling of very large timestamps.
Coding & AlgorithmsTechnical Screen - Hudson River TradingMediumSoftware EngineerFormat an Integer with Thousands Separators
Implement a function that formats a signed integer with a custom thousands separator character without relying on built-in string formatting utilities.
Coding & AlgorithmsTechnical Screenstringmathimplementation - Hudson River TradingMediumQuantitative ResearcherImplement Buffer Parsers and Generic Map Class
This problem tests your ability to safely parse binary data streams from raw memory buffers and implement a type-safe generic wrapper around standard associative containers.
Coding & AlgorithmsOnline AssessmentC++TemplatesBinary-Parsing - Hudson River TradingHardSoftware EngineerImplement Order Modification Feature
This question evaluates a software engineering competency in modifying and extending a C++ client/server trading system, focusing on state management, input validation, API integration, and maintaining invariants for order lifecycle.
Coding & AlgorithmsOnsite - Hudson River TradingEasySoftware EngineerMaximize Item Counts Under Suffix Budget Queries
Determine the maximum number of items that can be purchased from a suffix of an item array within a given budget for multiple independent queries.
Coding & AlgorithmsHR Screengreedysortingbinary-search - Hudson River TradingMediumSoftware EngineerReturn the K Smallest Integers
Implement an algorithm to extract the k smallest integers from an unsorted list in ascending order, preserving duplicates, and analyze the trade-offs between sorting, heaps, quickselect, and bounded-range approaches.
Coding & AlgorithmsTechnical ScreenHeapQuickselectSorting - Hudson River TradingMediumSoftware EngineerSimulate Alternating Stick Collection for a Nest
Tests simulation logic, two-pointer state management, turn alternation, and handling conditional decision rules with edge cases.
Coding & AlgorithmsTechnical ScreenTwo PointersSimulationGreedy - Hudson River TradingMediumSoftware EngineerSimulate Players Moving Under a Watcher's Gaze
Simulate the movement and freezing of players on a 1D track under the gaze of a moving watcher who reverses direction at specified times.
Coding & AlgorithmsTechnical Screensimulationarraystwo-pointers - Hudson River TradingEasySoftware EngineerSmallest Integer Point Lit by the Most Street Lamps on a Line
Online assessment coding problem: street lamps on a number line each light a closed interval around their position, and you must return the integer point lit by the most lamps, choosing the smallest such point on ties. It tests interval overlap counting over very large coordinate ranges.
Coding & AlgorithmsTechnical Screen - Hudson River TradingMediumSoftware EngineerSolve Watcher Simulation And Integer Conversion
This question evaluates event-driven simulation and discrete-time state modeling for tracking multiple agents under dynamic visibility constraints, together with low-level numeric string conversion and edge-case handling for 32-bit signed integers.
Coding & AlgorithmsTechnical Screen - Hudson River TradingMediumSoftware EngineerTest easy–medium array/string tasks
This question evaluates a candidate's ability to design concise, robust test cases and translate edge-case reasoning into concrete inputs and expected outputs for array and string problems, reflecting skills in input validation, correctness assurance, and handling varied data characteristics.
Coding & AlgorithmsTechnical Screen - IBMMediumSoftware EngineerBreak Adjacent Duplicate Characters
Tests string traversal, run-length counting, and greedy optimization to determine the minimum character replacements needed to eliminate adjacent identical characters across a list of words.
Coding & AlgorithmsOnline AssessmentStringsGreedyAlgorithms - IBMEasySoftware EngineerCalculate Revenue from Highest-Inventory VM Sales
Sell each VM unit at its current inventory count, always choose a type with maximum inventory, and compute total revenue safely.
Coding & AlgorithmsOnline Assessment - IBMMediumSoftware EngineerCount Employees With Unbroken Renewable Access at the Last Timestamp
A simulation problem about an access system where each employee's access lasts a fixed duration after every setting and can be extended only while it is still active. It asks how many employees hold valid access at the last timestamp, testing exact expiry boundaries, permanent lapses and per-employee state.
Coding & AlgorithmsTechnical Screen - IBMMediumSoftware EngineerCount Index Triplets Whose Max Minus Min Is at Most d
A counting problem that asks how many triplets of positions in an integer array have a spread, the largest value minus the smallest, of at most d. It tests handling duplicates and inclusive bounds, producing a count that can exceed 32 bits, and meeting time limits for arrays of up to 100,000 elements.
Coding & AlgorithmsTechnical Screen - IBMMediumSoftware EngineerCount Replacements Needed to Separate Equal Adjacent Characters
This problem tests your ability to identify and process consecutive character runs in strings and apply greedy calculations to minimize replacement operations.
Coding & AlgorithmsOnline AssessmentGreedyStringsArray - IBMMediumSoftware EngineerCount Seat-Price Trios Within a Budget Spread
Count how many trios of resale-marketplace seat listings have prices within a fixed budget spread of each other, using sorting and a two-pointer sweep instead of an O(n^3) scan.
Coding & AlgorithmsTechnical Screensortingtwo-pointerscombinatorics - IBMMediumSoftware EngineerCount Sensor Trios Within a Tolerance Band
Count how many groups of three readings stay inside a tolerance band (max minus min within a limit). Tests sorting, a sliding window, combinatorial counting and handling of duplicates and large totals.
Coding & AlgorithmsTechnical Screensortingtwo-pointerscombinatorics - IBMMediumSoftware EngineerCount Tree Vertices with Pythagorean Distances
Calculate distances from three fixed vertices to all other vertices in an unweighted tree and count those whose strictly positive distances form a Pythagorean triple.
Coding & AlgorithmsOnline AssessmentTreesBFSGraph - IBMMediumSoftware EngineerFind minimum subarray length with k distinct integers
This question tests proficiency with the sliding window technique and hash map-based frequency tracking, applied to subarray problems requiring exact cardinality constraints. It assesses the ability to distinguish between "exactly k distinct" and "at most k distinct" variants — a nuance that reveals depth in algorithmic thinking commonly evaluated in software engineering interviews.
Coding & AlgorithmsTechnical Screen - IBMMediumSoftware EngineerFunction Signature Lookup with Exact and Variadic Parameter Matching
A coding question about an IDE-style signature lookup engine: given registered functions, some whose last parameter is variadic, return for each call the sorted names of every function that accepts its argument types. It tests exact type-sequence matching, zero-or-more variadic arguments and edge cases such as empty argument lists.
Coding & AlgorithmsTechnical Screen - IBMMediumSoftware EngineerManage Authentication Tokens with a Fixed Time to Live
Design an authentication token manager that handles token generation, renewal, and active token counting based on a fixed time-to-live.
Coding & AlgorithmsOnline AssessmentHash MapDesignQueue - IBMMediumSoftware EngineerMaximize Revenue from Depleting VM Inventory
This problem tests your ability to efficiently manage and update a dynamic collection of items using a priority queue to always extract the maximum value.
Coding & AlgorithmsOnline AssessmentBinary SearchGreedyOptimization - IBMMediumSoftware EngineerMaximize Revenue from Depleting VM Stock
Tests greedy optimization, sorting, and arithmetic progression math to compute maximum revenue from diminishing-value stock with large order quantities.
Coding & AlgorithmsOnline Assessmentgreedybinary-searchmath - IBMMediumSoftware EngineerMaximize palindromic strings after character swaps
This question evaluates proficiency in string manipulation, combinatorial character-count reasoning, and redistribution of characters under constrained swap operations within the Coding & Algorithms domain.
Coding & AlgorithmsTechnical Screen - IBMEasySoftware EngineerSum Pairwise Remainders Across Two Integer Ranges
Calculate the total sum of remainders obtained by taking each integer in a dividend range modulo each non-zero divisor in a divisor range. The problem tests division properties, edge-case handling for zero divisors, and avoiding integer overflow.
Coding & AlgorithmsOnline AssessmentMathAlgorithmsArithmetic - IBMEasySoftware EngineerSum the XOR of Every Cross-Array Pair
Tests bitwise frequency analysis and arithmetic optimization by reducing an O(N * M) cross-product XOR sum to an O(B * (N + M)) bit-by-bit contribution calculation.
Coding & AlgorithmsOnline Assessmentbit-manipulationmatharrays
Hudson River Trading
IBM