Problems
Callback's own problems and the LeetCode questions companies have been asking, in one place — filter by category, company, topic, difficulty, and how recently a question showed up.
Asked on LeetCode
2,011 questions at Amazon · all time
- Check Knight Tour ConfigurationmediumArrayDepth-First SearchBreadth-First SearchMatrix+1frequency 5.0
- Check if Matrix Is X-MatrixeasyArrayMatrixfrequency 5.0
- Check if Strings Can be Made Equal With Operations IImediumHash TableStringSortingfrequency 5.0
- Check if a String Is an Acronym of WordseasyArrayStringfrequency 5.0
- Check if the Rectangle Corner Is ReachablehardArrayMathDepth-First SearchBreadth-First Search+2frequency 5.0
- Collect Coins in a TreehardArrayTreeGraph TheoryTopological Sortfrequency 5.0
- Collecting ChocolatesmediumArrayEnumerationfrequency 5.0
- Complete Binary Tree InsertermediumTreeBreadth-First SearchDesignBinary Treefrequency 5.0
- Concatenate Array With ReverseeasyArraySimulationfrequency 5.0
- Concatenate Non-Zero Digits and Multiply by Sum IeasyMathfrequency 5.0
- Consecutive CharacterseasyStringfrequency 5.0
- Construct Binary Tree from Preorder and Postorder TraversalmediumArrayHash TableDivide and ConquerTree+1frequency 5.0
- Convert 1D Array Into 2D ArrayeasyArrayMatrixSimulationfrequency 5.0
- Convert Binary Search Tree to Sorted Doubly Linked ListmediumLinked ListStackTreeDepth-First Search+3frequency 5.0
- Count AnagramshardHash TableMathStringCombinatorics+2frequency 5.0
- Count Array Pairs Divisible by KhardArrayHash TableMathCounting+3frequency 5.0
- Count Beautiful Splits in an ArraymediumArrayDynamic Programmingfrequency 5.0
- Count Collisions on a RoadmediumStringStackSimulationfrequency 5.0
- Count Days Without MeetingsmediumArraySortingfrequency 5.0
- Count Good MealsmediumArrayHash Tablefrequency 5.0
- Count Good Triplets in an ArrayhardArrayBinary SearchDivide and ConquerBinary Indexed Tree+3frequency 5.0
- Count Number of Ways to Place HousesmediumDynamic Programmingfrequency 5.0
- Count Numbers with Unique DigitsmediumMathDynamic ProgrammingBacktrackingfrequency 5.0
- Count Partitions with Even Sum DifferenceeasyArrayMathPrefix Sumfrequency 5.0
- Count Prefix and Suffix Pairs IeasyArrayStringTrieRolling Hash+2frequency 5.0
- Count Sub IslandsmediumArrayDepth-First SearchBreadth-First SearchUnion-Find+1frequency 5.0
- Count Subarrays With Majority Element IIhardArrayHash TableDivide and ConquerSegment Tree+2frequency 5.0
- Count Submatrices With Equal Frequency of X and YmediumArrayMatrixPrefix Sumfrequency 5.0
- Count Substrings That Can Be Rearranged to Contain a String ImediumHash TableStringSliding Windowfrequency 5.0
- Count Unguarded Cells in the GridmediumArrayMatrixSimulationfrequency 5.0
- Count the Number of Arrays with K Matching Adjacent ElementshardMathCombinatoricsFermat's Little Theoremfrequency 5.0
- Count the Number of Computer Unlocking PermutationsmediumArrayMathBrainteaserCombinatoricsfrequency 5.0
- Count the Number of InversionshardArrayDynamic Programmingfrequency 5.0
- Couples Holding HandshardGreedyDepth-First SearchBreadth-First SearchUnion-Find+1frequency 5.0
- Cyclically Rotating a GridmediumArrayMatrixSimulationfrequency 5.0
- Decode Ways IIhardStringDynamic Programmingfrequency 5.0
- Decoded String at IndexmediumStringStackfrequency 5.0
- Delete Columns to Make Sorted IIIhardArrayStringDynamic Programmingfrequency 5.0
- Delete Duplicate Folders in SystemhardArrayHash TableStringDepth-First Search+3frequency 5.0
- Delete Greatest Value in Each RoweasyArraySortingHeap (Priority Queue)Matrix+1frequency 5.0
- Describe the PaintingmediumArrayHash TableSortingPrefix Sumfrequency 5.0
- Design Authentication ManagermediumHash TableLinked ListDesignDoubly-Linked Listfrequency 5.0
- Design Circular DequemediumArrayLinked ListDesignQueuefrequency 5.0
- Design Exam Scores TrackermediumArrayBinary SearchDesignPrefix Sumfrequency 5.0
- Design Movie Rental SystemhardArrayHash TableDesignHeap (Priority Queue)+1frequency 5.0
- Design SkiplisthardLinked ListDesignfrequency 5.0
- Design SpreadsheetmediumArrayHash TableStringDesign+1frequency 5.0
- Diagonal Traverse IImediumArraySortingHeap (Priority Queue)frequency 5.0
- Divide ChocolatehardArrayBinary Searchfrequency 5.0
- Divide Intervals Into Minimum Number of GroupsmediumArrayTwo PointersGreedySorting+2frequency 5.0
Listings only — titles, difficulty, and tags link out to LeetCode. Imported from the leetcode-company-wise-problems snapshot dated 1 June 2025. Frequency is that dataset's own relative score within a company and time range.