#arrays

163 arrays interview questions, asked at Amazon, Google, Meta and 22 more companies. Last asked Oct 2026.

Largest permutation after sorting one fixed-length windowCodingYou get a permutation of 1 to n and a window size w. Exactly once, choose a contiguous window of exactly w elements and sort the elements inside it. Return the lexicographically…
Last asked Oct 2026
Microorganisms eating neighbours: the largest survivorCodingMicroorganisms stand in a row. Each one has a family (a letter) and a size (a positive integer). A microorganism can eat the neighbour directly to its left or right when that…
Last asked Oct 2026
Paint house: cheapest daily colors with no repeat on consecutive daysCodingFor the next n days a store sells blue, green and red shirts, and you get three cost arrays, one per color, giving each color's price on each day. You buy exactly one shirt every…
Last asked Oct 2026
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
Sort an array with one misplaced elementCodingSort a nearly sorted array in which a single element sits out of place, faster than a full sort. Reported on 1point3acres' Glean bank; reconstructed in our own words.
Last asked Sep 2026
+1
Kth 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
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
Insert, delete and get random in O(1) with duplicatesCodingDesign a collection of integers that allows duplicates and supports, each in average O(1) time: 1. insert(val): add one copy of val; return whether val was absent before. 2…
Last asked Sep 2026
Can every car park with preferred spots and forward-only overflowCodingA one-way street has n spots numbered 0 to n - 1. Cars arrive in order; car i wants spot preferencesi, takes it if free, and otherwise drives forward to the next free spot. A car…
Last asked Sep 2026
Next greater element in a circular arrayCodingYou get an integer array that wraps around: after the last element, scanning continues from the first. For every index, return the first value strictly greater than its own that…
Last asked Sep 2026
Memory allocator: leftmost free block and free by ownerCodingA memory has n units, numbered 0 to n - 1, all free at the start. Process a list of operations in order, each producing one recorded value: 1. Allocate size units for an owner:…
Last asked Sep 2026
Are all values in a subarray distinct? Constant-time range queriesCodingGiven an integer array and a range l, r, decide whether no value appears twice among numsl..r. Then many ranges will be queried against the same array. Preprocess it so each query…
Last asked Sep 2026
Two sumCodingGiven an integer array and a target, return the indices of the two different elements that add up to the target; exactly one such pair exists. Then solve it without a hash map…
Last asked Sep 2026
2D max pooling that also returns where each maximum came fromCodingImplement 2D max pooling over a grid of integers: a k by k window moves across the grid with a given stride, and each window outputs its maximum. Follow-up: for every output cell…
Last asked Sep 2026
Sort a transformed arrayCodingGiven a sorted array and the coefficients a, b, c of f(x) = ax^2 + bx + c, apply f to every element and return the results in sorted order in O(n). Use two pointers from both…
Last asked Sep 2026
First value seen twice in a left-to-right scanCodingWalk an integer array from left to right and return the first value you meet for the second time, or -1 when no value repeats. The answer is decided by where the second occurrence…
Last asked Sep 2026
First missing positiveCodingGiven an unsorted list of integers that may include negatives, zeros, duplicates and values much larger than the list's length, return the smallest positive integer that does not…
Last asked Sep 2026
Jump game: can you reach the last index?CodingYou get a list of non-negative integers and start at index 0. numsi is the longest jump you may make from index i: you can move forward to any index up to i + numsi. Return…
Last asked Sep 2026
Longest all-equal array after merging neighbours into their sumsCodingYou may replace any run of adjacent elements with their sum. Make every element of the resulting array equal while keeping it as long as possible, and return that length. Only the…
Last asked Sep 2026
Most visited position on a circular trackCodingA race runs over a circular track of numbered sections, given as the order of sections it passes through. Return the section or sections visited most often. Only the title of this…
Last asked Sep 2026
Longest non-decreasing subarray after changing one elementCoding1. Warm-up: return the length of the longest run of consecutive elements that is strictly increasing. 2. Given an integer array, return the longest contiguous non-decreasing…
Last asked Aug 2026
Minimum adjacent swaps to group a binary arrayCodingGiven an array of 0s and 1s, return the fewest swaps of neighbouring elements that put all the 0s at one end and all the 1s at the other. Either order is allowed.
Last asked Aug 2026
Maximum subarray sum of an array repeated k timesCodingWrite an integer array out k times back to back and return the largest sum of a non-empty contiguous subarray of the result. Do it without building the repeated array, and explain…
Last asked Aug 2026
+1
Count the maximum in each queried suffixCodingYou are given an integer array nums of length n and an array query of 0-based start indices. For each index i in query, look at the suffix numsi, numsi+1, ..., numsn-1. Find the…
Last asked Aug 2026
+3
Fixed-capacity circular bufferCodingImplement a generic FIFO buffer with a fixed capacity, allocated once up front, with constant-time push and pop. Discuss how to signal full and empty and how the buffer would be…
Last asked Aug 2026
Fewest global replacements to group equal valuesCodingYou are given an integer array arr of length n. In one operation you pick two different values x and y that both currently appear in arr, and you change every occurrence of x into…
Last asked Aug 2026
Delete and earnCodingTaking a value x from the array earns x points but deletes every x - 1 and x + 1. Return the most points you can earn. Explain how this reduces to the house robber recurrence over…
Last asked Aug 2026
Rearrange an array so positive and negative numbers alternateCodingGiven an array with positive and negative numbers, reorder it so positives and negatives alternate. Clarify whether relative order must be kept and what to do when one sign has…
Last asked Aug 2026
Longest straight run of one color in a gridCodingGiven a grid of colors such as R, G and B, return the length of the longest line of cells with the same color, running horizontally, vertically or diagonally.
Last asked Aug 2026
Zipline between two trees maximizing height times spanCodingTrees stand one unit apart with heights heightsi. A zipline joins two different trees at one height, no higher than the shorter tree. Its value is that height times the distance…
Last asked Aug 2026
Earliest pair with a target sumCodingGiven an array of numbers and a target, find the pair of elements that sums to the target and appears earliest in the array.
Last asked Aug 2026
+2
Merge two sorted interval listsCodingImplement mergetwointervallists(a, b). Each argument is a list of intervals start, end with integer endpoints and start <= end. Each list is sorted by start, and no two intervals…
Last asked Aug 2026
Remove one point from a cover of integer intervalsCodingYou are given a list of non-overlapping half-open intervals. An interval start, end with start < end covers the integers start, start + 1, ..., end - 1. Reading the intervals in…
Last asked Aug 2026
Subarray sum equals kCodingCount the contiguous subarrays whose sum equals k; the array may contain negative numbers. Follow-ups: only report whether such a subarray exists, or return the longest one.
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
+2
Top k largest elementsCodingGiven an integer array nums and an integer k, return the k largest elements of nums. You may return them in any order. The result is a multiset. If a value appears several times…
Last asked Aug 2026
Longest run of identical consecutive itemsCodingGiven a sequence, such as a string or the list of shows a user watched in order, return the longest run of the same item repeated back to back: its length and the item (and its…
Last asked Jul 2026
Rearrange digits so no neighbours sum above nineCodingRearrange a list of digits so that no two adjacent digits sum to more than nine, or report that it cannot be done.
Last asked Jul 2026
Flatten a 2D array with removeCodingImplement a class Vector2D that walks a 2D list of integers row by row, left to right, and lets the caller delete values while walking. text Vector2D(vec: listlistint) rows may be…
Last asked Jul 2026
Two contiguous delivery routes with the most revenueCodingStops along a line each bring some revenue. Pick two contiguous routes (segments of stops) that do not overlap so that their total revenue is as large as possible.
Last asked Jul 2026
Count visible people in a lineCodingPeople stand in a line and heightsi is the height of the person at position i. Two people can see each other when nobody standing between them is taller than both of them. First…
Last asked Jul 2026
Running cost of streamed token usageCodingToken usage for model requests arrives as a stream of usage records rather than all at once. Compute what the usage costs, keeping the totals correct as each new record arrives…
Last asked Jul 2026
Cheapest round-trip flight from two price listsCodingdeparturei is the price of flying out on day i and arrivalj the price of flying back on day j. Return the cheapest total for a trip that returns after it departs, in one pass.
Last asked Jul 2026
Find every set in a hand of Set cardsCodingEach card in the game Set has four attributes (color, shape, number, shading), and each attribute takes one of three values, so a card is four numbers from 0 to 2. Three cards…
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
Sort colors in placeCodingYou get an array of records, each tagged red, green or blue. Sort it in place so all reds come first, then greens, then blues, in one pass and constant extra space (the Dutch…
Last asked Jun 2026
Max-score jumps with primes ending in 3CodingYou are given a non-empty integer array nums of length n. You stand on index 0 and must finish on index n - 1. From index i you may move forward in one of two ways: - Step: move…
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
Sort an array with rotate and flip operationsCodingYou are given an array arr of n distinct integers. You may apply two operations, and each one counts as one step: - Rotate: remove the first element and append it to the end. p…
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
Longest subarray with absolute difference within a limitCodingGiven an integer array and a limit, return the length of the longest contiguous subarray in which any two elements differ by at most limit. The expected answer is O(n): a sliding…
Last asked May 2026
Flower placement and directory deletionCodingTwo problems in one round: 1. A row of plots has some flowers planted already, and no two flowers may be next to each other. Decide whether n more flowers can be planted. 2. Given…
Last asked May 2026
+2
Insert, delete and get random in O(1)CodingDesign a set with insert(val), remove(val) and getrandom(), each in average O(1) time. getrandom returns each current element with equal probability.
Last asked May 2026
Merge three sorted arrays without duplicatesCodingMerge three sorted integer arrays into one sorted array that contains each value once. Walk the three arrays together in a single pass rather than concatenating and sorting.
Last asked Apr 2026
Set over a bounded range of integersCodingImplement a set of integers drawn from a known bounded range, with add, remove and contains.
Last asked Apr 2026
+1
3SumCodingReturn every unique triple of values in an integer array that adds up to zero, with no duplicate triples in the answer. Aim for O(n^2) time after sorting.
Last asked Apr 2026
Largest axis-aligned rectangle from pointsCodingYou are given a list of distinct points on a 2D integer grid. Each point is a pair x, y. Return the largest area of a rectangle whose sides are parallel to the x and y axes and…
Last asked Apr 2026
Lexicographically largest output from a spreading availability maskCodingA test-data service builds an output array S from two inputs: - arr, an array of n positive integers; - state, a string of length n made of '0' and '1'. statei = '1' means arri is…
Last asked Apr 2026
Sort colors (three-way partition in place)CodingAn array holds only three kinds of values, such as 0, 1 and 2. Sort it in place in one pass without a counting sort. Explain the Dutch national flag partition and its invariants.
Last asked Apr 2026
Remove duplicates from a sorted array in placeCodingRemove duplicates from a sorted array in place so each value appears once, and return the new length; the first part of the array must hold the unique values in order. Use O(1)…
Last asked Apr 2026
GPU clusters: capacity left per day and the best K-switch planCodingYou run a few GPU clusters with fixed daily capacities, for example 10, 20. Each day a list of usage records takes GPUs from clusters (a record names the day, the cluster and how…
Last asked Apr 2026
Maximum gapCodingGiven an unsorted array, return the largest difference between two neighbours in its sorted order, in linear time and space. The trick is bucket sort (pigeonhole): the maximum gap…
Last asked Apr 2026
Remove one link and split a gold chain evenlyCodingAn array describes a gold chain; each number is the weight of one link. You must remove one link, join the chain back together, and then cut it into two pieces of equal weight for…
Last asked Apr 2026
Shift security units left to protect the most populationCodingCities stand in a row, numbered 0 to n - 1. You are given an integer array population of length n (all values = 0) and a binary string unit of the same length. uniti == '1' means…
Last asked Apr 2026
Best time to buy and sell stockCodingGiven daily prices, return the most profit you can make. First allow any number of buy-then-sell transactions (holding one share at a time), then allow only one transaction.
Last asked Apr 2026
Rotate an image matrix 90 degrees in placeCodingRotate a square matrix by 90 degrees clockwise without allocating another matrix. Transpose it and then reverse each row, or rotate the four cells of each ring in place. Explain…
Last asked Apr 2026
+1
Balanced prefixes in a permutationCodingYou are given a permutation p of length n: every integer from 1 to n appears exactly once, in some order. Call a number k (with 1 <= k <= n) balanced if some contiguous subarray…
Last asked Apr 2026
Minimum range boosts to make server power non-decreasingCodingYou manage a row of n machines. Machine i has an integer capacity poweri. You want the capacities to be non-decreasing from left to right (poweri <= poweri+1 for every i). You may…
Last asked Mar 2026
Research OA: best value ratio, shuttle trips and grid commandsCodingA multi-part online assessment. 1. Given ratings and prices, return the index with the highest rating-to-price ratio, choosing the smaller index on ties. Compare the fractions…
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
Final discounted prices and the items sold at full priceCodingEach item in a list gets a discount equal to the price of the first later item that costs no more than it; items with no such later item sell at full price. Return the total paid…
Last asked Mar 2026
Split stays across two listingsCodingA vacation rental site wants to offer split stays: when no single home is free for a guest's whole trip, the guest stays in one home first and then moves to another. There are n…
Last asked Feb 2026
Largest subset of two-digit numbers sharing a digitCodingAn array holds only two-digit integers (10 to 99). Choose as many elements as you can such that every chosen number contains at least one common digit. Return the count; for 52…
Last asked Feb 2026
Apply range overwrite queriesCodingYou get an array and a list of queries (start, end, k), each setting every element between start and end to k. Return the array after all queries. The interviewer wanted the…
Last asked Feb 2026
+1
Grep with context linesCodingImplement a simplified grep. You get a list of text lines, a search string target, and a non-negative integer k. Return every line that contains target, together with up to k…
Last asked Feb 2026
+1
Find 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
Fewest deletions so a list's first k items avoid another listCodingYou get two lists, a and b, and an integer k. Delete elements from b so that none of the first k elements of what remains also appears in a. Return the fewest deletions needed (or…
Last asked Feb 2026
Remove duplicates in place from an unsorted arrayCodingRemove repeated values from an unsorted array in place, keeping the first occurrence of each and their order, and return the new length. Compare a hash set with sorting first, and…
Last asked Feb 2026
Next permutationCodingRearrange an array of numbers into the next permutation in lexicographic order, in place with constant extra memory; if it is the last permutation, wrap around to the smallest.
Last asked Feb 2026
Zero out duplicates and sort an arrayCodingGiven an unsorted array of about 75 integers that may contain duplicates, replace the repeated copies with zero and return the array sorted. Discuss the time and space of your…
Last asked Feb 2026
+2
Product of array except selfCodingReturn an array where each position holds the product of every other element, without division and in linear time, using prefix and suffix products; then do it with constant extra…
Last asked Feb 2026
Pour water onto a terrainCodingAn array gives the height of each column of a terrain. 1. Print the terrain. 2. Drop a given number of water units at a column, one at a time. Each unit moves left if it can…
Last asked Feb 2026
Final prices after next-lower-price discountsCodingYou get a list of prices. Each item is discounted by the first later price that is lower than it (agree whether an equal price counts); an item with no such price pays full price…
Last asked Feb 2026
Count subarrays that sum to KCodingGiven an array of integers (negatives allowed) and k, count the contiguous subarrays whose sum is exactly k. Keep running prefix sums and a map from each prefix sum to how often…
Last asked Feb 2026
Short systems utility tasks: spikes, logs and bracketsCodingSolve a few short utility problems: detect a sudden temperature spike in timestamped CPU readings, check that brackets in an expression balance, and aggregate log lines by status…
Last asked Feb 2026
Compress a vertex list into unique vertices and indicesCodingTurn a list of vertex tuples into a list of unique vertices in first-seen order plus an index array that rebuilds the original list.
Last asked Feb 2026
Best time to buy and sell stock: one trade, then twoCodingGiven a stock's daily prices, return the most profit you can make: 1. With one buy and one later sell. 2. With at most two non-overlapping trades.
Last asked Feb 2026
+1
Closest latency pairs by minimum absolute differenceCodingA monitoring service records latency readings (whole milliseconds) and wants to flag readings that are suspiciously close to one another. Implement minabsdiffpairs(latencies:…
Last asked Feb 2026
Sum of all consecutive-step subarraysCodingCall a subarray consecutive when each element is exactly one more than the one before it, or each is exactly one less (a single element counts). Return the sum of the values of…
Last asked Feb 2026
Merge two sorted arrays in placeCodingTwo integer arrays, arr1 and arr2, are each sorted in ascending order. Merge arr2 into arr1 without using another array, so that arr1 ends up holding all the values, still…
Last asked Feb 2026
Jump gameCodingEach element of an array is the maximum jump length from that position. Starting at index 0, decide whether you can reach the last index. Solve it greedily in O(n) by tracking the…
Last asked Feb 2026
Fewest jumps between two indices of a circular arrayCodingIn a circular array, arri is the exact distance you may jump from index i, either left or right, wrapping around the ends. Given a start index and a target index, return the…
Last asked Jan 2026
Playlist with add, remove and shuffleCodingImplement a video playlist that supports adding a title, removing a title and shuffling the order, along with playing the next title. Aim for constant-time add and remove, a fair…
Last asked Jan 2026
Print the odd numbers in a listCodingGiven a list of integers, print every odd number in it, in order. Mind negative numbers and an empty list.
Last asked Jan 2026
Pick the most profitable repeated queryCodingA data warehouse has a time budget of k minutes and n query types. Query type i takes timesi minutes per run and earns profitsi per completed run. You must commit to one query…
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
+1
Dot product of run-length encoded vectorsCodingA very long integer vector has many repeated values. Design a compact representation for it (for example, runs of value and count), then compute the dot product of two vectors…
Last asked Jan 2026
Fewest emergency restocks to keep inventory validCodingYour stock changes every day by taski (positive or negative). On days where taski == 0 the stock is checked and must not be negative, and at no time may the stock exceed…
Last asked Jan 2026
Score an array by taking the smallest and marking its neighboursCodingStart with every element of an array unmarked and a score of 0. Repeatedly pick the smallest unmarked value (the leftmost one on a tie), add it to the score, and mark it together…
Last asked Jan 2026
Range queries: is the subarray parity-alternatingCodingCall an array special when every pair of neighbouring elements has different parity (one odd, one even). Given an integer array and many queries from, to, answer for each query…
Last asked Jan 2026
Longest strictly increasing contiguous subarrayCodingReturn the length of the longest contiguous subarray whose elements strictly increase. Solve it in one pass and constant extra space, then discuss variants such as returning the…
Last asked Jan 2026
Set with constant-time insert, delete and get randomCodingDesign a set with add, remove and getrandom, all in average O(1); getrandom returns each element with equal probability. Handle empty-set and missing-element cases. Follow-up: how…
Last asked Jan 2026
Smallest starting index that never leaves on the leftCodingEach cell of an array holds a move: a positive number moves you that many cells right, a negative one moves you left. Starting from some index you keep following the moves. Find…
Last asked Dec 2025
+2
Find K pairs with the smallest sumsCodingGiven two sorted arrays and k, return the k pairs (one number from each array) with the smallest sums. Start a min-heap with pairs formed from the first elements and push the next…
Last asked Dec 2025
Four short array and string exercisesCodingFour quick problems in one round: 1. Return the difference between the number of uppercase and lowercase letters in a string. 2. Repeatedly subtract from the non-zero elements of…
Last asked Dec 2025
Two sum with the lexicographically smallest index pairCodingGiven an integer array and a target, return a pair of indices i < j whose values add up to the target. When several pairs work, return the lexicographically smallest one (smallest…
Last asked Dec 2025
Shuffle an array with a random-integer functionCodingUsing only a function that returns a uniform random integer in a range, shuffle an array (for example a deck of cards) so every permutation is equally likely. Implement…
Last asked Dec 2025
Longest vacation with N PTO daysCodingA year is given as an array of days, each a workday (W) or a holiday (H). You have n paid days off to place on workdays. Return the longest run of consecutive days off you can…
Last asked Nov 2025
Max profit when taking a value skips aheadCodingYou walk an array of positive integers from index 0. At index i you either take arri and jump to index i + 1 + arri, or skip it and move to i + 1. Return the largest total you can…
Last asked Oct 2025
Trapping rain waterCodingGiven bar heights in an elevation map, each of width 1, compute how much water is trapped after rain. Start with the brute-force solution and its complexity, then improve it to…
Last asked Sep 2025
Merge sorted arrayCodingMerge a sorted array into another sorted array that has room at its end, in place, and give the complexity. Follow-up reported: could you merge starting from the front of each…
Last asked Sep 2025
Missing rangesCodingGiven a sorted list of distinct integers inside a fixed range (for example 0 to 99), list the gaps. In the reported variant a gap of up to three numbers is written out number by…
Last asked Sep 2025
Longest subarray whose ends exceed everything betweenCodingGiven an integer array, return the length of the longest contiguous subarray whose first and last elements are both greater than every element strictly between them. Do better…
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
Cheapest round trip from departure and return faresCodingYou get two arrays of daily fares, one for departing flights and one for return flights. Choose a departure day and a later return day to minimize the total price. One pass that…
Last asked Sep 2025
Split a two-colour necklace fairly with two cutsCodingA necklace (a circle of beads) holds two kinds of gems, each in an even count. With at most two cuts, divide it into pieces and hand them to two people so each gets the same…
Last asked Sep 2025
Insert intervalCodingGiven a list of non-overlapping intervals sorted by start and a new interval, insert the new one and merge wherever it overlaps, returning a sorted list of non-overlapping…
Last asked Sep 2025
Check an array is a permutation of 0 to n-1CodingImplement iszerobasedpermutation(nums: listint) - bool. Given an integer array nums of length n, return True if it contains every integer from 0 to n - 1 exactly once, and False…
Last asked Sep 2025
Best time to buy and sell stock with a limited holding windowCodingA variant of the best time to buy and sell stock: one buy and one later sell, maximizing profit, with the sell restricted to a limited window after the buy. Explain how a…
Last asked Aug 2025
Shortest unsorted continuous subarrayCodingFind the shortest contiguous subarray that, if sorted, makes the whole array sorted, and return its length. Start from sorting a copy, then find an O(n) two-pointer solution.
Last asked Aug 2025
Most equal values after shifting one subarrayCodingGiven an array, you may once choose any contiguous subarray and add the same integer (positive or negative) to all of its elements. Return the largest number of equal values the…
Last asked Aug 2025
Sum of products over all subarraysCodingAn online assessment with two problems. 1. A simplified text justification: lay words out into lines of a fixed width. 2. Given an array, return the sum, over every contiguous…
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
Buildings with an ocean viewCodingBuildings stand in a row with the ocean to the right. A building has a view if every building to its right is shorter. Return the indices with a view in increasing order, scanning…
Last asked Aug 2025
Subarrays with power-of-two length and sum between K and 2KCodingGiven an integer array and k, find every contiguous subarray whose length is a power of two and whose sum lies between k and 2k. Use prefix sums so each candidate is checked in…
Last asked Aug 2025
Toeplitz matrixCodingReturn whether every diagonal of a matrix running from top-left to bottom-right holds a single repeated value, comparing each cell with the one up and to its left.
Last asked Aug 2025
Fewest passes to collect a permutation in orderCodingA shelf holds a permutation of 1..n. Starting with target 1, you scan the shelf left to right, and whenever you see the current target you take it and look for the next number…
Last asked Jul 2025
Count of smaller numbers after selfCodingFor every element of an integer array, count how many elements to its right are smaller, and return those counts. The O(n^2) scan is too slow; use merge sort that tracks original…
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
Sum of the longest run of positive numbersCodingAn array holds positive and negative numbers. Find the longest contiguous run of positive numbers and return its sum (decide and state how ties between equally long runs are…
Last asked Jul 2025
Count index pairs with an even product and odd distanceCodingGiven an integer array, count pairs i < j where numsi numsj is even and j - i is odd. Avoid checking every pair: count even and odd values by index parity and combine.
Last asked Jan 2025
One-dimensional array with distinct elementsCodingSolve an array task constrained to distinct elements, using hashing to enforce uniqueness in linear time. Reported on 1point3acres' Glean bank; reconstructed in our own words.
Two-dimensional array with distinct elementsCodingProcess a two-dimensional array tracking distinct elements per row or column. Reported on 1point3acres' Glean bank; reconstructed in our own words.
Maximum element in an arrayCodingReturn the largest element of an array in one pass. Reported on 1point3acres' Sierra bank; reconstructed in our own words.
Longest subsequence with at most k value changesCodingYou get an integer array elements and a non-negative integer k. Choose a subsequence of elements: delete any number of items (possibly none) and keep the rest in their original…
+1
Window with the most copies of a target valueCodingImplement mosttargetwindow(nums, targetindex, windowsize). The target value is numstargetindex. Look at every contiguous subarray of nums with exactly windowsize elements. Return…
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…
Split an array into two halves with equal sumsCodingYou are given an array nums of positive integers. Find an index i that splits it into two non-empty contiguous parts with the same sum: - the left part is nums0..i (it includes…
Place books on the least-full allowed shelfCodingYou have numshelves shelves, numbered 0 to numshelves - 1. All shelves start empty. Books arrive one at a time. Book i comes with a limit limitsi. It may only go on shelves 0…
One-hot encode an integer arrayCodingWrite onehot(arr: listint) - listlistint that returns the one-hot encoding of an integer array as a 2D list. - The matrix has one row per element of arr, in the same order. - It…
Count warehouse robots boxed in on all four sidesCodingA warehouse floor is modeled as an integer grid. Each delivery robot sits at a point (xi, yi), and no two robots share a point. A robot is idle when there is at least one other…
Minimum swaps to put evens before oddsCodingGiven an integer array nums of length n, you want every even value to come before every odd value. In one move you may swap the values at any two distinct indices. Return the…
Minimum starting battery for a task queueCodingA server runs a queue of jobs strictly in order, powered by one battery. Job i changes the battery by -usagei: a positive usagei drains the battery, and a negative one means the…
Split parcels into the most balanced shipmentsCodingParcels sit on a conveyor in a fixed order, and weightsi is the weight of the i-th parcel. You must cut the line into contiguous shipments so that every parcel belongs to exactly…
Maximize total cluster throughput from median-of-three serversCodingYou manage a fleet of host servers. hostThroughputi is the throughput of server i (a non-negative integer). Group servers into clusters of exactly three distinct servers. Build as…
Levels cleared from every starting pointCodingA game has n levels in a row. You are given two integer arrays of length n, layers and energy, and an integer K. A run that starts at level i begins with exactly K energy and…
Max flight distance with limited energyCodingYou are planning a trip over n days. disti is how far you can fly on day i (a non-negative integer). You start with k units of energy, and k is also the most energy you can hold…
Fewest decrements to make an array a 1-to-k-to-1 pyramidCodingYou are given an array arr of n non-negative integers. One operation picks any index and lowers that element by exactly 1. Elements can never be raised. Return the minimum number…
Pick the highest-scoring movie row by top-k similarityCodingA user just finished a movie they liked. Your recommender already scored every other title for how similar it is to that movie, and the catalog is split into curated groups (rows…
Garage occupancy at every timestampCodingA parking garage records occupancy over n discrete timestamps, numbered 0 to n - 1. You get a list of parking tickets. Ticket entry, exit means one car arrived at timestamp entry…
Largest subset with a non-zero bitwise ANDCodingGiven an array arr of positive integers, choose as many elements as you can so that the bitwise AND of all chosen elements is greater than 0. The chosen elements can come from…
Fewest range increments to build a target arrayCodingYou start with an array of n zeros. In one move you choose a contiguous range l, r and add 1 to every element in it. Given a non-negative integer array target of length n…
Greatest three-digit subsequenceCodingYou are given a list digits of single digits (each 0–9). Choose at most three of them, keep them in their original order, and read them left to right as a number. Return the…
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Count distinct values in every sliding windowCodingGiven an integer array nums and a window size k, return a list with one entry per contiguous window of length k (there are len(nums) - k + 1 of them). Each entry is the number of…
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…
Which prefixes of 1..n appear as a contiguous blockCodingYou are given an array p of length n that is a permutation of the integers 1..n (each value appears exactly once). For every k from 1 to n, decide whether p has a contiguous…
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Cake order fulfillment checkCodingA bakery keeps three kinds of cake. Its stock is an array stock of length 3, where stocki is how many cakes of type i are on hand. Orders arrive one at a time in the list orders…
Build the longest spike from an arrayCodingA spike is a sequence of integers that strictly increases up to a single peak and then strictly decreases. The peak belongs to both parts, and either part may be empty, so a…
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…
Longest run of customers a bank can serveCodingA bank opens with initial dollars in its vault (initial = 0). Customers wait in a fixed queue, given as an integer array transactions: a positive value is a deposit and a negative…
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Merge two sorted arrays into distinct valuesCodingTwo integer arrays, nums1 and nums2, are each sorted in non-decreasing order and may contain repeated values. Return one array, sorted in ascending order, that contains every…
Count stable server segmentsCodingA row of n machines has integer capacities capacity0..n-1. A contiguous segment l, r is stable when all of these hold: 1. It contains at least 3 machines (r - l = 2). 2. The two…