The most frequently asked interview problems at top tech companies. Curated and categorized.
Q001Two SumArrays & Hashing
GoogleAmazonMeta
Easy Q002Add Two NumbersLinked Lists
AmazonMicrosoft
Medium Q003Longest Substring Without Repeating CharactersSliding Window
AmazonGoogleMeta
Medium Q004Median of Two Sorted ArraysBinary Search
GoogleAmazon
Hard Q005Longest Palindromic SubstringStrings
AmazonMetaMicrosoft
Medium Q006Reverse IntegerMath
AmazonBloomberg
Medium Q007String to Integer (atoi)Strings
MicrosoftAmazon
Medium Q008Palindrome NumberMath
Amazon
Easy Q009Regular Expression MatchingDynamic Programming
GoogleAmazonMeta
Hard Q010Container With Most WaterTwo Pointers
AmazonGoogleMeta
Medium Q0113SumTwo Pointers
AmazonGoogleMeta
Medium Q012Letter Combinations of a Phone NumberBacktracking
AmazonGoogle
Medium Q013Generate ParenthesesBacktracking
AmazonGoogleMeta
Medium Q014Merge K Sorted ListsLinked Lists
AmazonGoogleMeta
Hard Q015Valid ParenthesesStack
AmazonMetaBloomberg
Easy Q016Merge Two Sorted ListsLinked Lists
AmazonMicrosoft
Easy Q017Best Time to Buy and Sell StockDynamic Programming
AmazonMeta
Easy Q018Climbing StairsDynamic Programming
AmazonGoogle
Easy Q019Maximum SubarrayDynamic Programming
AmazonGoogleMicrosoft
Medium Q020Jump GameGreedy
AmazonGoogle
Medium Q021Merge IntervalsIntervals
AmazonGoogleMeta
Medium Q022Unique PathsDynamic Programming
AmazonGoogle
Medium Q023Minimum Path SumDynamic Programming
AmazonGoogle
Medium Q024Sort ColorsTwo Pointers
AmazonMicrosoft
Medium Q025SubsetsBacktracking
AmazonGoogle
Medium Q026Word SearchBacktracking
AmazonMicrosoft
Medium Q027CandyGreedy
Amazon
Hard Q028Trapping Rain WaterTwo Pointers
AmazonGoogleMeta
Hard Q029Binary Tree Maximum Path SumTrees
GoogleMeta
Hard Q030Serialize and Deserialize Binary TreeTrees
AmazonGoogleMeta
Hard Q031Valid Binary Search TreeTrees
AmazonGoogleMeta
Medium Q032Lowest Common Ancestor of a Binary TreeTrees
AmazonGoogleMeta
Medium Q033Binary Tree Level Order TraversalTrees
AmazonGoogle
Medium Q034Convert Sorted Array to Binary Search TreeTrees
Amazon
Easy Q035Maximum Depth of Binary TreeTrees
AmazonGoogle
Easy Q036Invert Binary TreeTrees
Google
Easy Q037Same TreeTrees
Amazon
Easy Q038Number of IslandsGraphs
AmazonGoogleMeta
Medium Q039Clone GraphGraphs
AmazonMeta
Medium Q040Course ScheduleGraphs
AmazonGoogleMeta
Medium Q041Pacific Atlantic Water FlowGraphs
GoogleAmazon
Medium Q042Word LadderGraphs
AmazonGoogleMeta
Hard Q043Implement Trie (Prefix Tree)Trie
AmazonGoogle
Medium Q044Design Add and Search Words Data StructureTrie
AmazonMeta
Medium Q045Word Search IITrie
AmazonGoogleMeta
Hard Q046Top K Frequent ElementsHeap
AmazonMetaGoogle
Medium Q047Find Median from Data StreamHeap
AmazonGoogleMeta
Hard Q048Task SchedulerHeap
MetaAmazon
Medium Q049LRU CacheDesign
AmazonGoogleMeta
Medium Q050Min StackStack
AmazonMicrosoft
Medium Q051Evaluate Reverse Polish NotationStack
Amazon
Medium Q052Daily TemperaturesStack
AmazonGoogle
Medium Q053Car FleetStack
Amazon
Medium Q054Largest Rectangle in HistogramStack
AmazonGoogle
Hard Q055Sliding Window MaximumSliding Window
AmazonGoogleMeta
Hard Q056Minimum Window SubstringSliding Window
AmazonMetaMicrosoft
Hard Q057Longest Repeating Character ReplacementSliding Window
Google
Medium Q058Permutation in StringSliding Window
Amazon
Medium Q059Best Time to Buy and Sell Stock with CooldownDynamic Programming
Google
Medium Q060Coin ChangeDynamic Programming
AmazonGoogle
Medium Q061Longest Increasing SubsequenceDynamic Programming
AmazonGoogleMeta
Medium Q062Word BreakDynamic Programming
AmazonGoogleMeta
Medium Q063House RobberDynamic Programming
Amazon
Medium Q064Unique Binary Search TreesDynamic Programming
Amazon
Medium Q065Decode WaysDynamic Programming
AmazonGoogle
Medium Q066Longest Common SubsequenceDynamic Programming
AmazonGoogle
Medium Q067Edit DistanceDynamic Programming
AmazonGoogle
Medium Q068Interleaving StringDynamic Programming
AmazonGoogle
Hard Q069Burst BalloonsDynamic Programming
Amazon
Hard Q070Longest Valid ParenthesesDynamic Programming
AmazonGoogle
Hard Q071Median of a Sorted MatrixBinary Search
Google
Hard Q072Koko Eating BananasBinary Search
Google
Medium Q073Search in Rotated Sorted ArrayBinary Search
AmazonGoogle
Medium Q074Find Minimum in Rotated Sorted ArrayBinary Search
AmazonGoogle
Medium Q075Time Based Key-Value StoreBinary Search
Google
Medium Q076Design TwitterDesign
Amazon
Medium Q077Design Underground SystemDesign
Meta
Medium Q078Snapshot ArrayDesign
Meta
Medium Q079All O'one Data StructureDesign
Amazon
Hard Q080LRU Cache Doubly Linked ListLinked Lists
AmazonMicrosoft
Medium Q081Reverse Nodes in k-GroupLinked Lists
AmazonMeta
Hard Q082Swap Nodes in PairsLinked Lists
Amazon
Medium Q083Rotate ListLinked Lists
Amazon
Medium Q084Remove Nth Node From End of ListLinked Lists
AmazonGoogle
Medium Q085Reorder ListLinked Lists
AmazonMeta
Medium Q086Palindrome Linked ListLinked Lists
AmazonMeta
Easy Q087Missing NumberMath
AmazonMicrosoft
Easy Q088Counting BitsBit Manipulation
Amazon
Easy Q089Sum of Two IntegersBit Manipulation
Amazon
Medium Q090Reverse BitsBit Manipulation
Amazon
Easy Q091Single NumberBit Manipulation
AmazonGoogle
Easy Q092Number of 1 BitsBit Manipulation
Amazon
Easy Q093Alien DictionaryGraphs
AmazonGoogleMeta
Hard Q094Graph Valid TreeGraphs
AmazonGoogle
Medium Q095Number of Connected ComponentsGraphs
AmazonGoogle
Medium Q096Rotting OrangesGraphs
AmazonGoogle
Medium Q097Redundant ConnectionGraphs
Amazon
Medium Q098Accounts MergeGraphs
AmazonGoogle
Medium Q099Is Graph BipartiteGraphs
AmazonGoogle
Medium Q100Longest Increasing Path in a MatrixGraphs
AmazonGoogleMeta
Hard