Median of several sorted arraysCodingYou get several integer arrays, each sorted in non-decreasing order. Return the median of all their values taken together. The interview started with exactly two arrays and then…
Last asked Oct 2026
#binary-search
+2Memory allocator with malloc, free and coalescingCodingManage one arena of size bytes, addressed by offset from 0. You hand out and take back ranges of it, like malloc and free in C. Nothing is stored in the arena itself; track it in…Last asked Oct 2026
+1Kth largest element in two sorted arraysCodingFind the kth largest element across two sorted arrays without merging them. Reported on 1point3acres' Glean bank; reconstructed in our own words.Last asked Sep 2026- Divide a bar into k+1 pieces to maximize the smallest pieceCodingAn array of positive integers describes consecutive chunks of a bar. Make exactly k cuts so the bar becomes k + 1 contiguous pieces, and you keep the piece with the smallest sum…Last asked Sep 2026
+4Maximum overlap of closed intervalsCodingGiven a list of closed intervals start, end (both endpoints included), return the largest number of intervals that contain one point on the number line. Two intervals that only…Last asked Sep 2026
Squares of a sorted array, then the k smallest squaresCodingYou get an integer array sorted in non-decreasing order; it may hold negative numbers. 1. Return the squares of all its elements in sorted order, faster than sorting again (O(n)…Last asked Sep 2026
+2Banking system with transfers, cashback and account mergesCodingBuild an in-memory banking system in four levels. Each level adds methods, and every earlier method must keep working. Every call takes a timestamp in milliseconds as its first…Last asked Sep 2026- +1Social follow graph with point-in-time snapshotsCodingBuild an in-memory follow graph that can answer questions about its own past. Follows are directed: a following b says nothing about b following a. Implement a SocialNetwork…Last asked Sep 2026
- +1Guess the number with one-call delayed feedbackCodingA hidden integer secret lies in 1, n, inclusive. You can't read it. The only way to learn about it is a comparison service with one method: The service answers one call late. Each…Last asked Sep 2026
+1Customer revenue with referral credit and bottom-k queryCodingBuild an in-memory system that tracks how much revenue each customer brings in, including revenue from the customers they referred. Customers get integer ids starting at 0, in the…Last asked Sep 2026- Distributed mode and median across worker shardsCodingYou are given a cluster of k worker nodes, numbered 0 to k - 1. Each worker holds its own unsorted slice (shard) of a large integer dataset. A worker can read only its own shard…Last asked Sep 2026
- Grid path from start to target, then the path farthest from a catCodingAn N x N grid has a start cell S, a target cell T, water cells and land cells. You move one step up, down, left or right and can never enter water. 1. Decide whether you can get…Last asked Sep 2026
+1Weighted job schedulingCodingEach job has a start time, an end time and a profit. Choose jobs that do not overlap to make the most profit. Sort jobs by end time; for each job, binary search for the last job…Last asked Sep 2026
+1Lowest horizontal line that splits squares into equal areasCodingSeveral axis-aligned squares are given by their bottom-left corner and side length. Find the lowest horizontal line y = h such that the total square area below the line equals the…Last asked Sep 2026- Character at an index of a run-length encoded stringCodingA string is stored run-length encoded, like "B1A2E3C1" for BAAEEEC. Return the character at a given index without decoding the string. Follow-up: many queries; precompute prefix…Last asked Sep 2026
House robber IV: smallest possible maximum over k non-adjacent picksCodingA row of houses (or servers) each holds a value. Choose at least k of them with no two next to each other. Among all valid choices, make the largest chosen value as small as…Last asked Sep 2026
+8Temporal key-value store with point-in-time reads and restoreCodingBuild an in-memory key-value store that keeps every version of every key, so you can ask what a key held at any point in time. Implement the TemporalKVStore class: -…Last asked Sep 2026
Find bad GPU nodes with group testsCodingA cluster has n GPU nodes with ids 0 to n - 1. Each node is either good or bad, and you do not know which in advance. The only way to learn anything is a test service: A failing…Last asked Sep 2026- Add one delivery center to minimize the worst distanceCodingA grid marks delivery centers with 1 and every other cell with 0. The distance between two cells is max(x1 - x2, y1 - y2) (moving in all eight directions). The grid's…Last asked Sep 2026
- +1Meeting room scheduler over a fixed set of roomsCodingImplement a MeetingScheduler for a fixed set of meeting rooms. Each room has a unique string ID. - MeetingScheduler(roomids: liststr) sets up the rooms. Room IDs are unique. -…Last asked Aug 2026
Find a local minimum or peak with binary searchCodingFind any local minimum of an array, an element no larger than its neighbours (treat positions outside the array as infinitely large), in O(log n) time. The same idea finds a peak…Last asked Aug 2026- Check a new interval against existing ones for conflictsCodingGiven a set of existing intervals, decide whether a new interval overlaps any of them. Then discuss answering many such checks quickly as intervals keep being added, for example…Last asked Aug 2026
- Longest equal length for cutting wood into K piecesCodingYou get pieces of wood of different lengths. Cut them into at least K pieces that all have the same length; leftover bits may be thrown away. Return the largest length that works…Last asked Aug 2026
- Capacity to ship packages within D daysCodingPackages stand in a line with known weights and must be shipped in that order, one trip a day, by a ship with a fixed weight capacity. Return the smallest capacity that ships…Last asked Aug 2026
- Indexed sequence with checkpointsCodingBuild a growable array that can take cheap snapshots. The spec arrives in three parts; finish and test each part before the next. Part 1. append(value) - index, pop() - value…Last asked Jul 2026
- Reach a target when you can only step between nearby pointsCodingYou get a set of unordered points, a start point, an end point, and a function getDistance(x, y). You can step from one point to another only when their distance is within a…Last asked Jul 2026
Weighted random pick with add and removeCoding1. Given positive weights, return a random index with probability proportional to its weight. 2. Turn it into a structure of weighted keys that supports adding a key, removing a…Last asked Jul 2026
+1Random pick weighted by populationCodingGiven countries and their populations, write a picker that returns a random country with probability proportional to its population. Build prefix sums once, draw a random number…Last asked Jul 2026- Single element in a sorted arrayCodingIn a sorted array where every value appears exactly twice except one, find the value that appears once, in logarithmic time.Last asked Jun 2026
- +1Maximize pipeline throughput within a scaling budgetCodingA message pipeline has n services in series, and every message passes through all of them. The pipeline's throughput is therefore the minimum throughput of any service. You are…Last asked Jun 2026
- Which interval contains a number?CodingBuild a class with addNonOverlappingInterval(start, end) and a query that says whether a number falls inside a stored interval (and which one). Discuss three versions: a linear…Last asked Jun 2026
- Horizontal line that splits the area of rectangles in halfCodingGiven axis-aligned rectangles, find the lowest horizontal line y = c for which the total rectangle area above the line equals the total area below it. Discuss how overlapping…Last asked Jun 2026
- Find the closest version by dateCodingGiven versions and their release dates, return the version whose date is closest to a query date.Last asked Jun 2026
- Minimum processing rate to finish before a deadlineCodingGiven a list of jobs of different sizes and a deadline in hours, find the smallest processing rate that finishes every job in time, when each hour works on a single job at that…Last asked May 2026
- Minimum eating rate to finish in timeCodingYou have piles of work (in the classic version, piles of bananas) and h hours. Each hour you process up to k units from a single pile. Find the smallest whole-number rate k that…Last asked May 2026
- Leftmost column with a one in a row-sorted binary matrixCodingIn an m x n matrix of 0s and 1s, each row has all its 0s before its 1s. Return the index of the leftmost column that holds a 1, or -1 if there is none. Start with a binary search…Last asked May 2026
- Minimize a black-box convex functionCodingYou are given a black-box function F that is convex on a closed interval a, b. You cannot see its formula or its derivative. The only way to learn about it is to call evaluate(x)…Last asked May 2026
- +1Find a local minimum in an arrayCodingReturn the index of any element smaller than its neighbours (the ends compare with their one neighbour). A linear scan works; the follow-up is logarithmic time by binary searching…Last asked Apr 2026
- Russian doll envelopesCodingEach envelope has a width and a height. One fits inside another when both its width and height are strictly smaller. Return the largest number of envelopes you can nest one inside…Last asked Mar 2026
- Earliest release that supports a featureCodingYou ship a library whose releases are listed in versions, sorted from oldest to newest. Each entry is a "MAJOR.MINOR.PATCH" string; parts are non-negative integers and may be…Last asked Mar 2026
- Count distinct values in a sorted arrayCodingCount the distinct values in a sorted array of length n that holds only k distinct values, where k is much smaller than n. A linear scan works; do better by jumping over each run…Last asked Mar 2026
- Max purchases from a sorted price rowCodingA market hall has n stalls in a row, numbered 1..n. Stall i sells a single kind of item at price pricesi-1, and the prices are non-decreasing from left to right. A shopper may buy…Last asked Mar 2026
+1Find first and last position of an element in a sorted arrayCodingGiven an array of integers sorted in non-decreasing order and a target value, return the index of the first and the last occurrence of the target, or -1, -1 when it is absent. The…Last asked Feb 2026- Grid path that keeps its highest cell as low as possibleCodingEach cell of an m x n grid holds a height. Find a path from the top-left to the bottom-right cell, moving up, down, left or right, whose highest cell is as low as possible, and…Last asked Feb 2026
- Find when failures started in a logCodingA service writes a time-ordered log of request results, and at some point it started failing. Find the moment the failures began. Discuss the approach when you can only read the…Last asked Jan 2026
- Maximize the minimum asset value within an upgrade budgetCodingYou hold a portfolio of n assets. Asset i is currently worth valuesi. You can upgrade any asset as many times as you like. Each upgrade of asset i costs costsi and adds valuesi to…Last asked Jan 2026
- Find the conflicting pair of tests with a black-box runnerCodingA black-box run(tests) runs a set of tests together and reports failure when the set contains a conflicting pair of tests; any test alone passes. Find the conflicting pair with as…Last asked Jan 2026
- H-index of instance ratingsCodingGiven the integer ratings of a set of instances, return the largest integer k such that at least k instances have a rating of k or more (return 0 when no such k exists). Do it…Last asked Jan 2026
- Median of two run-length encoded arraysCodingTwo sorted arrays are given in run-length form (value and count pairs). Return the median of all their values combined, without expanding the runs. Explain how binary search on…Last asked Jan 2026
- Weighted random value generatorCodingGiven values with positive weights, write a generator that returns a value at random with probability proportional to its weight. Build it once and answer many calls quickly, and…Last asked Jan 2026
- Longest duplicated substringCodingReturn any longest substring that occurs at least twice in a string (the occurrences may overlap), or an empty string if none does. Binary search on the length with a rolling…Last asked Dec 2025
- +2Count intervals covering a pointCodingBuild a data structure over a fixed list of closed intervals on the integer number line that answers many point queries quickly. An interval l, r covers a point x when l <= x <=…Last asked Nov 2025
- My calendar: book without double bookingCodingBuild a calendar whose book(start, end) accepts a half-open interval only if it does not overlap any existing booking. Compare a list scan with a sorted structure and binary…Last asked Nov 2025
- Most consecutive elements from an index whose sum stays below a targetCodingYou get a non-decreasing array, a start index and a target. Return how many consecutive elements, starting at that index, can be added while the sum stays below the target. Use…Last asked Nov 2025
- Random pick with weightCodingGiven positive weights, implement pick() that returns index i with probability wi / sum(w). Build prefix sums once, then binary search a random number into them. One version gives…Last asked Oct 2025
- Minimum hourly rate to empty every vault in timeCodingA row of vaults holds vaultsi units each, and there are h hours. Each hour you can take up to k units from one vault only; leftover capacity in that hour does not carry over to…Last asked Sep 2025
Find the first error in a log, then trace failures through dependenciesCoding1. A service's log lines are tagged Info, Warn or Error. Once the first Error appears the service is down, so every later line is an Error too, and the line just before the first…Last asked Sep 2025- Cutting ribbonsCodingYou have pieces of wood (or ribbon) of given lengths and need k pieces of equal length; you may cut but not join. Return the longest length that still yields at least k pieces…Last asked Sep 2025
- Fewest days to deliver every order from distribution centersCodingThere are N distribution centers numbered 1..N and a list of orders, each naming a destination city numbered like the centers. Each day a center can work on one order: delivering…Last asked Sep 2025
- Task delay times from the farthest smaller priorityCodingTask priorities are given in an array and processed from right to left. A task's delay time is the distance from it to the farthest task on its right that has a smaller priority…Last asked Sep 2025
- Earliest time a password becomes irrecoverableCodingA password is attacked one character at a time: you get the order in which positions are replaced by '', one per second. The password counts as irrecoverable once at least m of…Last asked Sep 2025
- Kth smallest element in a sorted matrixCodingEvery row and every column of an n x n matrix is sorted ascending. Return the k-th smallest value. Compare a min-heap over the rows with binary search on the value range.Last asked Sep 2025
- Lower and upper bound binary searchCodingGiven an array sorted in non-decreasing order and a target, return the first index whose value is at least the target and the first index whose value is greater than the target…Last asked Sep 2025
- Search a sorted array of unknown lengthCodingA sorted array can only be read through get(i), which signals when i is past the end; you do not know the length. Return the index of a target value or -1. Find a range that…Last asked Sep 2025
Distance to the nearest waypoint along a routeCodingYou are writing part of a car's navigation software. A route is a polyline: an ordered list of 2D waypoints coordinates, connected by straight segments from each waypoint to the…Last asked Aug 2025- Median of two sorted arraysCodingGiven two sorted arrays, return the median of their combined values. Start from merging and its cost, then reach logarithmic time with a binary search over the partition of the…Last asked Aug 2025
- Key-value map with snapshotsCodingBuild a key-value map that supports set, get and snapshot. snapshot() returns an ID, and you can then read what any key held as of that snapshot. Avoid copying the whole map at…Last asked Aug 2025
- Budget queries on a sorted price list, then a shortest pathCodingTwo problems in a 90-minute assessment. First, items come sorted by price; for each budget query, return how many items you can buy. A knapsack DP is too slow; prefix sums with…Last asked Aug 2025
- Count distinct values in a sorted array with few distinct valuesCodingA sorted array is huge but holds only a handful of distinct values. Count the distinct values faster than scanning every element: from each new value, binary search (or gallop) to…Last asked Aug 2025
- Target indices after sorting an arrayCodingReturn the indices at which a target would sit once the array is sorted. In the reported version the array is already sorted and the answer must take logarithmic time: binary…Last asked Jul 2025
- Most days picking distinct productsCodingYou have quantities of several products. On day i (starting at 1) you must pick exactly i items, each from a different product, out of what is left. Return the largest number of…Last asked Jul 2025
- Longest increasing subarray and subsequenceCodingTwo warm-ups on one array: 1. The longest strictly increasing contiguous run (for 1, 2, 1, 2, 3 it is 1, 2, 3). 2. The longest increasing subsequence, whose elements need not be…Last asked Jul 2025
- Random point in non-overlapping squaresCodingDefine a class for a square on the plane and return a uniformly random point inside it. Follow-up: given many non-overlapping squares, return a point that is uniformly random over…Last asked Jul 2025
- Koko eating bananasCodingThere are piles of bananas and h hours. Each hour Koko eats up to k bananas from one pile. Return the smallest integer k that lets her finish every pile within h hours. Binary…Last asked Jan 2025
- Minimum daily reading pace to finish a textbookCodingA student must read a textbook of n chapters before an exam. Chapter i has pagesi pages, and the chapters must be read in order. The student picks a daily limit x. On each day…
- +1Shortest equal length for two boards covering every holeCodingA table top has holes at integer positions along a single line, given as an unsorted array holes (positions may repeat or be negative). You will patch it with exactly two boards…
- Fit the most tasks into an hour across machine slotsCodingYour team runs a batch cluster of n machines with IDs 0 to n-1. Each machine has m execution slots, so it can run up to m tasks at the same time. A slot runs one task at a time;…
- Largest square from 1x1 and 2x2 tilesCodingYou have M small tiles of size 1×1 and N large tiles of size 2×2. Build the largest possible square: every cell of the square must be covered by exactly one tile, with no gaps, no…
- Smallest free hub for a taskCodingYou run a fleet of n compute hubs, numbered 0 to n - 1, and need to place one new task on a single hub. You are given: - capacities: an integer list of length n. capacitiesi is…
- Recent file tracker with date and insertion orderCodingImplement a FileStorageSystem class that records files and answers two kinds of listing queries. - storefile(file: str, date: str) - None records a file with its storage date…
- Days needed to finish recurring tasksCodingYou run n recurring tasks. Task i runs for the first time on day 1 and then again every intervalsi days, so it runs on days 1, 1 + intervalsi, 1 + 2 intervalsi, .... Any number of…
- First occurrence or floor index in a sorted arrayCodingYou are given an array nums of integers sorted in non-decreasing order. It may contain repeated values. You are also given an integer target. Implement searchfirstorfloor(nums…