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Array Interview Questions

240 Array problems asked across FAANG and top tech companies. Approach hints, optimal solutions, and related problems.

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Array 240
ArrayClear all
1.Two Sum
ArrayHash Table
Easy+10▶ Mock
56.Merge Intervals
ArraySorting
Medium+14▶ Mock
121.Best Time to Buy and Sell Stock
ArrayDynamic Programming
Easy+10▶ Mock
15.3Sum
ArrayTwo PointersSorting
Medium+5▶ Mock
11.Container With Most Water
ArrayTwo PointersGreedy
Medium+6▶ Mock
42.Trapping Rain Water
ArrayTwo PointersStack
Hard+6▶ Mock
4.Median of Two Sorted Arrays
ArrayBinary SearchDivide and Conquer
Hard+5▶ Mock
347.Top K Frequent Elements
ArrayHash TableHeap
Medium+6▶ Mock
128.Longest Consecutive Sequence
ArrayHash TableUnion Find
Medium+3▶ Mock
198.House Robber
Dynamic ProgrammingArray
Medium+1▶ Mock
560.Subarray Sum Equals K
ArrayHash TablePrefix Sum
Medium+2▶ Mock
33.Search in Rotated Sorted Array
ArrayBinary Search
Medium+5▶ Mock
53.Maximum Subarray
ArrayDynamic ProgrammingDivide and Conquer
Medium+7▶ Mock
238.Product of Array Except Self
ArrayPrefix Sum
Medium+5▶ Mock
739.Daily Temperatures
StackArray
Medium+4▶ Mock
253.Meeting Rooms II
ArrayHeapSorting
Medium+6▶ Mock
134.Gas Station
ArrayGreedy
Medium+5▶ Mock
152.Maximum Product Subarray
ArrayDynamic Programming
Medium+4▶ Mock
283.Move Zeroes
ArrayTwo Pointers
Easy▶ Mock
45.Jump Game II
ArrayDynamic ProgrammingGreedy
Medium▶ Mock
34.Find First and Last Position of Element in Sorted Array
ArrayBinary Search
Medium+1▶ Mock
1146.Snapshot Array
ArrayHash TableBinary Search
Medium▶ Mock
75.Sort Colors
ArrayTwo PointersSorting
Medium▶ Mock
14.Longest Common Prefix
ArrayStringTrie
Easy+1▶ Mock
26.Remove Duplicates from Sorted Array
ArrayTwo Pointers
Easy+1▶ Mock
79.Word Search
ArrayStringBacktracking
Medium+1▶ Mock
189.Rotate Array
ArrayMathTwo Pointers
Medium+1▶ Mock
88.Merge Sorted Array
ArrayTwo PointersSorting
Easy+1▶ Mock
54.Spiral Matrix
ArrayMatrixSimulation
Medium+2▶ Mock
78.Subsets
ArrayBacktrackingBit Manipulation
Medium▶ Mock
215.Kth Largest Element in an Array
ArrayDivide and ConquerSorting
Medium▶ Mock
122.Best Time to Buy and Sell Stock II
ArrayDynamic ProgrammingGreedy
Medium▶ Mock
399.Evaluate Division
ArrayStringDepth-First Search
Medium▶ Mock
380.Insert Delete GetRandom O(1)
ArrayHash TableMath
Medium▶ Mock
721.Accounts Merge
ArrayHash TableString
Medium▶ Mock
2502.Design Memory Allocator
ArrayHash TableDesign
Medium+1▶ Mock
239.Sliding Window Maximum
ArrayQueueSliding Window
Hard+2▶ Mock
1929.Concatenation of Array
ArraySimulation
Easy▶ Mock
904.Fruit Into Baskets
ArrayHash TableSliding Window
Medium▶ Mock
167.Two Sum II - Input Array Is Sorted
ArrayTwo PointersBinary Search
Medium▶ Mock
977.Squares of a Sorted Array
ArrayTwo PointersSorting
Easy▶ Mock
31.Next Permutation
ArrayTwo Pointers
Medium▶ Mock
875.Koko Eating Bananas
ArrayBinary Search
Medium▶ Mock
735.Asteroid Collision
ArrayStackSimulation
Medium+1▶ Mock
169.Majority Element
ArrayHash TableDivide and Conquer
Easy▶ Mock
362.Design Hit Counter
ArrayBinary SearchDesign
Medium▶ Mock
410.Split Array Largest Sum
ArrayBinary SearchDynamic Programming
Hard▶ Mock
41.First Missing Positive
ArrayHash Table
Hard▶ Mock
2639.Find the Width of Columns of a Grid
ArrayMatrix
Easy▶ Mock
2408.Design SQL
ArrayHash TableString
Medium▶ Mock
2035.Partition Array Into Two Arrays to Minimize Sum Difference
ArrayBinary SearchDynamic Programming
Hard▶ Mock
2503.Maximum Number of Points from Grid Queries
ArrayTwo PointersBreadth-First Search
Hard▶ Mock
1962.Remove Stones to Minimize the Total
ArrayGreedyHeap
Medium▶ Mock
3471.Find the Largest Almost Missing Integer
ArrayHash Table
Easy▶ Mock
40.Combination Sum II
ArrayBacktracking
Medium▶ Mock
1091.Shortest Path in a Binary Matrix
ArrayBreadth-First SearchMatrix
Medium▶ Mock
1429.First Unique Number
ArrayHash TableDesign
Medium▶ Mock
704.Binary Search
ArrayBinary Search
Easy▶ Mock
300.Longest Increasing Subsequence
ArrayBinary SearchDynamic Programming
Medium▶ Mock
1049.Last Stone Weight II
ArrayDynamic ProgrammingKnapsack
Medium▶ Mock
503.Next Greater Element II
ArrayStackMonotonic Stack
Medium▶ Mock
303.Range Sum Query - Immutable
ArrayDesignPrefix Sum
Easy▶ Mock
2402.Meeting Rooms III
ArrayHash TableSorting
Hard▶ Mock
48.Rotate Image
ArrayMathMatrix
Medium▶ Mock
1046.Last Stone Weight
ArrayHeap
Easy▶ Mock
219.Contains Duplicate II
ArrayHash TableSliding Window
Easy▶ Mock
1335.Minimum Difficulty of a Job Schedule
ArrayDynamic Programming
Hard▶ Mock
68.Text Justification
ArrayStringSimulation
Hard▶ Mock
217.Contains Duplicate
ArrayHash TableSorting
Easy▶ Mock
39.Combination Sum
ArrayBacktracking
Medium▶ Mock
3484.Design Spreadsheet
ArrayHash TableString
Medium▶ Mock
631.Design Excel Sum Formula
ArrayHash TableString
Hard▶ Mock
900.RLE Iterator
ArrayDesignCounting
Medium▶ Mock
3043.Find the Length of the Longest Common Prefix
ArrayHash TableString
Medium▶ Mock
16.3Sum Closest
ArrayTwo PointersSorting
Medium▶ Mock
18.4Sum
ArrayTwo PointersSorting
Medium▶ Mock
870.Advantage Shuffle
ArrayTwo PointersGreedy
Medium▶ Mock
526.Beautiful Arrangement
ArrayDynamic ProgrammingBacktracking
Medium▶ Mock
1966.Binary Searchable Numbers in an Unsorted Array
ArrayBinary SearchStack
Medium▶ Mock
815.Bus Routes
ArrayHash TableBreadth-First Search
Hard▶ Mock
605.Can Place Flowers
ArrayGreedy
Easy▶ Mock
1011.Capacity To Ship Packages Within D Days
ArrayBinary Search
Medium▶ Mock
1752.Check if Array Is Sorted and Rotated
Array
Easy▶ Mock
1386.Cinema Seat Allocation
ArrayHash TableGreedy
Medium▶ Mock
427.Construct Quad Tree
ArrayDivide and ConquerTree
Medium▶ Mock
3875.Construct Uniform Parity Array I
ArrayMath
Easy▶ Mock
220.Contains Duplicate III
ArraySliding WindowSorting
Hard▶ Mock
3067.Count Pairs of Connectable Servers in a Weighted Tree Network
ArrayTreeDepth-First Search
Medium▶ Mock
2444.Count Subarrays With Fixed Bounds
ArrayQueueSliding Window
Hard▶ Mock
2954.Count the Number of Infection Sequences
ArrayMathCombinatorics
Hard▶ Mock
2559.Count Vowel Strings in Ranges
ArrayStringPrefix Sum
Medium▶ Mock
740.Delete and Earn
ArrayHash TableDynamic Programming
Medium▶ Mock
2353.Design a Food Rating System
ArrayHash TableString
Medium▶ Mock
353.Design Snake Game
ArrayHash TableDesign
Medium▶ Mock
348.Design Tic-Tac-Toe
ArrayHash TableDesign
Medium▶ Mock
271.Encode and Decode Strings
ArrayStringDesign
Medium▶ Mock
636.Exclusive Time of Functions
ArrayStack
Medium▶ Mock
1475.Final Prices With a Special Discount in a Shop
ArrayStackMonotonic Stack
Easy▶ Mock
55.Jump Game
ArrayDynamic ProgrammingGreedy
Medium▶ Mock
153.Find Minimum in Rotated Sorted Array
ArrayBinary Search
Medium▶ Mock
162.Find Peak Element
ArrayBinary Search
Medium▶ Mock
57.Insert Interval
Array
Medium▶ Mock
986.Interval List Intersections
ArrayTwo PointersSweep Line
Medium▶ Mock
84.Largest Rectangle in Histogram
ArrayStackMonotonic Stack
Hard▶ Mock
289.Game of Life
ArrayMatrixSimulation
Medium▶ Mock
287.Find the Duplicate Number
ArrayTwo PointersBinary Search
Medium▶ Mock
179.Largest Number
ArrayStringGreedy
Medium▶ Mock
213.House Robber II
ArrayDynamic Programming
Medium▶ Mock
1048.Longest String Chain
ArrayHash TableTwo Pointers
Medium▶ Mock
845.Longest Mountain in Array
ArrayTwo PointersDynamic Programming
Medium▶ Mock
658.Find K Closest Elements
ArrayTwo PointersBinary Search
Medium▶ Mock
2933.High-Access Employees
ArrayHash TableString
Medium▶ Mock
609.Find Duplicate File in System
ArrayHash TableString
Medium▶ Mock
2812.Find the Safest Path in a Grid
ArrayBinary SearchBreadth-First Search
Medium▶ Mock
1438.Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit
ArrayQueueSliding Window
Medium▶ Mock
2373.Largest Local Values in a Matrix
ArrayMatrix
Easy▶ Mock
1004.Max Consecutive Ones III
ArrayBinary SearchSliding Window
Medium▶ Mock
643.Maximum Average Subarray I
ArraySliding Window
Easy▶ Mock
1200.Minimum Absolute Difference
ArraySorting
Easy▶ Mock
983.Minimum Cost For Tickets
ArrayDynamic Programming
Medium▶ Mock
628.Maximum Product of Three Numbers
ArrayMathSorting
Easy▶ Mock
3914.Minimum Operations to Make Array Non Decreasing
ArrayGreedy
Medium▶ Mock
209.Minimum Size Subarray Sum
ArrayBinary SearchSliding Window
Medium▶ Mock
2461.Maximum Sum of Distinct Subarrays With Length K
ArrayHash TableSliding Window
Medium▶ Mock
849.Maximize Distance to Closest Person
Array
Medium▶ Mock
46.Permutations
ArrayBacktracking
Medium▶ Mock
66.Plus One
ArrayMath
Easy▶ Mock
2551.Put Marbles in Bags
ArrayGreedySorting
Hard▶ Mock
1366.Rank Teams by Votes
ArrayHash TableString
Medium▶ Mock
2561.Rearranging Fruits
ArrayHash TableGreedy
Hard▶ Mock
27.Remove Element
ArrayTwo Pointers
Easy▶ Mock
51.N-Queens
ArrayBacktrackingAlgorithm X
Hard▶ Mock
857.Minimum Cost to Hire K Workers
ArrayGreedySorting
Hard▶ Mock
1928.Minimum Cost to Reach Destination in Time
ArrayDynamic ProgrammingGraph
Hard▶ Mock
871.Minimum Number of Refueling Stops
ArrayDynamic ProgrammingGreedy
Hard▶ Mock
827.Making A Large Island
ArrayDepth-First SearchBreadth-First Search
Hard▶ Mock
3035.Maximum Palindromes After Operations
ArrayHash TableString
Medium▶ Mock
3893.Maximum Team Size with Overlapping Intervals
ArraySortingUnion Find
Medium▶ Mock
3634.Minimum Removals to Balance Array
ArrayBinary SearchSliding Window
Medium▶ Mock
2366.Minimum Replacements to Sort the Array
ArrayMathGreedy
Hard▶ Mock
3413.Maximum Coins From K Consecutive Bags
ArrayBinary SearchGreedy
Medium▶ Mock
3953.Maximum Score with Co-Prime Element
ArrayHash TableMath
Hard▶ Mock
3387.Maximize Amount After Two Days of Conversions
ArrayStringDepth-First Search
Medium▶ Mock
2251.Number of Flowers in Full Bloom
ArrayHash TableBinary Search
Hard▶ Mock
305.Number of Islands II
ArrayHash TableUnion Find
Hard▶ Mock
3649.Number of Perfect Pairs
ArrayMathTwo Pointers
Medium▶ Mock
1944.Number of Visible People in a Queue
ArrayStackMonotonic Stack
Hard▶ Mock
1639.Number of Ways to Form a Target String Given a Dictionary
ArrayStringDynamic Programming
Hard▶ Mock
465.Optimal Account Balancing
ArrayDynamic ProgrammingBacktracking
Hard▶ Mock
74.Search a 2D Matrix
ArrayBinary SearchMatrix
Medium▶ Mock
35.Search Insert Position
ArrayBinary Search
Easy▶ Mock
73.Set Matrix Zeroes
ArrayHash TableMatrix
Medium▶ Mock
136.Single Number
ArrayBit Manipulation
Easy▶ Mock
912.Sort an Array
ArrayDivide and ConquerSorting
Medium▶ Mock
36.Valid Sudoku
ArrayHash TableMatrix
Medium▶ Mock
228.Summary Ranges
Array
Easy▶ Mock
645.Set Mismatch
ArrayHash TableBit Manipulation
Easy▶ Mock
3718.Smallest Missing Multiple of K
ArrayHash Table
Easy▶ Mock
713.Subarray Product Less Than K
ArrayBinary SearchSliding Window
Medium▶ Mock
692.Top K Frequent Words
ArrayHash TableString
Medium▶ Mock
384.Shuffle an Array
ArrayMathDesign
Medium▶ Mock
1010.Pairs of Songs With Total Durations Divisible by 60
ArrayHash TableCounting
Medium▶ Mock
737.Sentence Similarity II
ArrayHash TableString
Medium▶ Mock
1101.The Earliest Moment When Everyone Become Friends
ArrayUnion FindSorting
Medium▶ Mock
2039.The Time When the Network Becomes Idle
ArrayBreadth-First SearchGraph
Medium▶ Mock
1970.Last Day Where You Can Still Cross
ArrayBinary SearchDepth-First Search
Hard▶ Mock
1428.Leftmost Column with at Least a One
ArrayBinary SearchMatrix
Medium▶ Mock
2213.Longest Substring of One Repeating Character
ArrayStringSegment Tree
Hard▶ Mock
2948.Make Lexicographically Smallest Array by Swapping Elements
ArrayUnion FindSorting
Medium▶ Mock
332.Reconstruct Itinerary
ArrayStringDepth-First Search
Hard▶ Mock
354.Russian Doll Envelopes
ArrayBinary SearchDynamic Programming
Hard▶ Mock
1293.Shortest Path in a Grid with Obstacles Elimination
ArrayBreadth-First SearchMatrix
Hard▶ Mock
2718.Sum of Matrix After Queries
ArrayHash Table
Medium▶ Mock
1258.Synonymous Sentences
ArrayHash TableString
Medium▶ Mock
980.Unique Paths III
ArrayBacktrackingBit Manipulation
Hard▶ Mock
140.Word Break II
ArrayHash TableString
Hard▶ Mock
Missing Number
ArrayHash TableMath
Easy▶ Mock
Word Search II
ArrayStringBacktracking
Hard+1▶ Mock
64.Minimum Path Sum
ArrayDynamic ProgrammingMatrix
Medium▶ Mock
118.Pascal's Triangle
ArrayDynamic Programming
Easy▶ Mock
149.Max Points on a Line
ArrayHash TableMath
Hard▶ Mock
240.Search a 2D Matrix II
ArrayBinary SearchDivide and Conquer
Medium▶ Mock
243.Shortest Word Distance
ArrayString
Easy▶ Mock
244.Shortest Word Distance II
ArrayHash TableTwo Pointers
Medium▶ Mock
381.Insert Delete GetRandom O(1) - Duplicates allowed
ArrayHash TableMath
Hard▶ Mock
475.Heaters
ArrayTwo PointersBinary Search
Medium▶ Mock
494.Target Sum
ArrayDynamic ProgrammingBacktracking
Medium▶ Mock
496.Next Greater Element I
ArrayHash TableStack
Easy▶ Mock
528.Random Pick with Weight
ArrayMathBinary Search
Medium▶ Mock
622.Design Circular Queue
ArrayLinked ListDesign
Medium▶ Mock
706.Design HashMap
ArrayHash TableLinked List
Easy▶ Mock
723.Candy Crush
ArrayTwo PointersMatrix
Medium▶ Mock
749.Contain Virus
ArrayDepth-First SearchBreadth-First Search
Hard▶ Mock
773.Sliding Puzzle
ArrayDynamic ProgrammingBacktracking
Hard▶ Mock
851.Loud and Rich
ArrayDepth-First SearchGraph
Medium▶ Mock
853.Car Fleet
ArrayStackSorting
Medium▶ Mock
928.Minimize Malware Spread II
ArrayHash TableDepth-First Search
Hard▶ Mock
973.K Closest Points to Origin
ArrayMathDivide and Conquer
Medium▶ Mock
974.Subarray Sums Divisible by K
ArrayHash TablePrefix Sum
Medium▶ Mock
1029.Two City Scheduling
ArrayGreedySorting
Medium▶ Mock
1043.Partition Array for Maximum Sum
ArrayDynamic Programming
Medium▶ Mock
1086.High Five
ArrayHash TableSorting
Easy▶ Mock
1125.Smallest Sufficient Team
ArrayDynamic ProgrammingBit Manipulation
Hard▶ Mock
1202.Smallest String With Swaps
ArrayHash TableString
Medium▶ Mock
1235.Maximum Profit in Job Scheduling
ArrayBinary SearchDynamic Programming
Hard▶ Mock
1248.Count Number of Nice Subarrays
ArrayHash TableMath
Medium▶ Mock
1298.Maximum Candies You Can Get from Boxes
ArrayBreadth-First SearchGraph
Hard▶ Mock
1352.Product of the Last K Numbers
ArrayMathDesign
Medium▶ Mock
1353.Maximum Number of Events That Can Be Attended
ArrayGreedySorting
Medium▶ Mock
1434.Number of Ways to Wear Different Hats to Each Other
ArrayDynamic ProgrammingBit Manipulation
Hard▶ Mock
1482.Minimum Number of Days to Make m Bouquets
ArrayBinary Search
Medium▶ Mock
1535.Find the Winner of an Array Game
ArraySimulation
Medium▶ Mock
1564.Put Boxes Into the Warehouse I
ArrayGreedySorting
Medium▶ Mock
1610.Maximum Number of Visible Points
ArrayMathGeometry
Hard▶ Mock
1642.Furthest Building You Can Reach
ArrayGreedyHeap
Medium▶ Mock
1648.Sell Diminishing-Valued Colored Balls
ArrayMathBinary Search
Medium▶ Mock
1710.Maximum Units on a Truck
ArrayGreedySorting
Easy▶ Mock
1751.Maximum Number of Events That Can Be Attended II
ArrayBinary SearchDynamic Programming
Hard▶ Mock
1762.Buildings With an Ocean View
ArrayStackMonotonic Stack
Medium▶ Mock
1823.Find the Winner of the Circular Game
ArrayMathRecursion
Medium▶ Mock
1828.Queries on Number of Points Inside a Circle
ArrayMathGeometry
Medium▶ Mock
1834.Single-Threaded CPU
ArraySortingHeap
Medium▶ Mock
2043.Simple Bank System
ArrayHash TableDesign
Medium▶ Mock
2050.Parallel Courses III
ArrayDynamic ProgrammingGraph
Hard▶ Mock
2101.Detonate the Maximum Bombs
ArrayMathDepth-First Search
Medium▶ Mock
2171.Removing Minimum Number of Magic Beans
ArrayGreedySorting
Medium▶ Mock
2237.Count Positions on Street With Required Brightness
ArrayPrefix Sum
Medium▶ Mock
2303.Calculate Amount Paid in Taxes
ArraySimulation
Easy▶ Mock
2439.Minimize Maximum of Array
ArrayBinary SearchDynamic Programming
Medium▶ Mock
2491.Divide Players Into Teams of Equal Skill
ArrayHash TableTwo Pointers
Medium▶ Mock
2672.Number of Adjacent Elements With the Same Color
Array
Medium▶ Mock
2680.Maximum OR
ArrayGreedyBit Manipulation
Medium▶ Mock
2895.Minimum Processing Time
ArrayGreedySorting
Medium▶ Mock
2964.Number of Divisible Triplet Sums
ArrayHash Table
Medium▶ Mock
3076.Shortest Uncommon Substring in an Array
ArrayHash TableString
Medium▶ Mock
3078.Match Alphanumerical Pattern in Matrix I
ArrayHash TableString
Medium▶ Mock
3092.Most Frequent IDs
ArrayHash TableHeap
Medium▶ Mock
3161.Block Placement Queries
ArrayBinary SearchBinary Indexed Tree
Hard▶ Mock
3208.Alternating Groups II
ArraySliding Window
Medium▶ Mock
3919.Minimum Cost to Move Between Indices
ArrayPrefix Sum
Medium▶ Mock

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