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
298 questions at Apple · all time
- LRU CachemediumHash TableLinked ListDesignDoubly-Linked Listfrequency 100.0
- Two SumeasyArrayHash Tablefrequency 86.9
- Merge IntervalsmediumArraySortingQuicksortfrequency 84.5
- Number of IslandsmediumArrayDepth-First SearchBreadth-First SearchUnion-Find+1frequency 84.5
- Best Time to Buy and Sell StockeasyArrayDynamic Programmingfrequency 79.3
- Design Hit CountermediumArrayBinary SearchDesignQueue+1frequency 79.3
- Rotate ArraymediumArrayMathTwo Pointersfrequency 78.2
- Group AnagramsmediumArrayHash TableStringSortingfrequency 77.6
- Top K Frequent ElementsmediumArrayHash TableDivide and ConquerSorting+4frequency 77.0
- Longest Common PrefixeasyArrayStringTriefrequency 76.4
- Reverse Linked ListeasyLinked ListRecursionfrequency 75.8
- Valid SudokumediumArrayHash TableMatrixfrequency 75.8
- Course Schedule IImediumDepth-First SearchBreadth-First SearchGraph TheoryTopological Sortfrequency 73.0
- Course SchedulemediumDepth-First SearchBreadth-First SearchGraph TheoryTopological Sort+1frequency 72.2
- Valid ParentheseseasyStringStackBracket Sequencesfrequency 71.5
- Valid PalindromeeasyTwo PointersStringfrequency 70.6
- Product of Array Except SelfmediumArrayPrefix Sumfrequency 69.8
- Kth Largest Element in an ArraymediumArrayDivide and ConquerSortingHeap (Priority Queue)+1frequency 68.0
- Maximum SubarraymediumArrayDivide and ConquerDynamic Programmingfrequency 68.0
- Reverse Words in a StringmediumTwo PointersStringfrequency 68.0
- Spiral MatrixmediumArrayMatrixSimulationfrequency 68.0
- Time Based Key-Value StoremediumHash TableStringBinary SearchDesignfrequency 68.0
- Longest Substring Without Repeating CharactersmediumHash TableStringSliding Windowfrequency 67.0
- Merge k Sorted ListshardLinked ListDivide and ConquerHeap (Priority Queue)Merge Sort+1frequency 67.0
- Best Time to Buy and Sell Stock IImediumArrayDynamic ProgrammingGreedyfrequency 66.0
- Reverse IntegermediumMathfrequency 66.0
- Rotate ImagemediumArrayMathMatrixfrequency 66.0
- Subarray Product Less Than KmediumArrayBinary SearchSliding WindowPrefix Sumfrequency 64.9
- Find First and Last Position of Element in Sorted ArraymediumArrayBinary Searchfrequency 63.7
- Median of Two Sorted ArrayshardArrayBinary SearchDivide and Conquerfrequency 63.7
- Meeting Rooms IImediumArrayTwo PointersGreedySorting+2frequency 63.7
- Subarray Sum Equals KmediumArrayHash TablePrefix Sumfrequency 63.7
- Trapping Rain WaterhardArrayTwo PointersDynamic ProgrammingStack+1frequency 63.7
- Design Circular QueuemediumArrayLinked ListDesignQueuefrequency 62.5
- Insert Delete GetRandom O(1)mediumArrayHash TableMathDesign+1frequency 62.5
- Lowest Common Ancestor of a Binary TreemediumTreeDepth-First SearchBinary TreeBinary Lifting+1frequency 62.5
- Move ZeroeseasyArrayTwo Pointersfrequency 62.5
- Reverse BitseasyDivide and ConquerBit Manipulationfrequency 62.5
- Merge Two Sorted ListseasyLinked ListRecursionfrequency 61.2
- Snapshot ArraymediumArrayHash TableBinary SearchDesign+1frequency 61.2
- Basic Calculator IImediumMathStringStackfrequency 59.9
- Find Median from Data StreamhardTwo PointersDesignSortingHeap (Priority Queue)+1frequency 59.9
- Min StackmediumStackDesignfrequency 59.9
- Word LadderhardHash TableStringBreadth-First SearchBidirectional Searchfrequency 59.9
- Merge Sorted ArrayeasyArrayTwo PointersSortingfrequency 58.4
- Word BreakmediumArrayHash TableStringDynamic Programming+3frequency 58.4
- 3SummediumArrayTwo PointersSortingfrequency 56.8
- Climbing StairseasyMathDynamic ProgrammingMemoizationfrequency 56.8
- Design Tic-Tac-ToemediumArrayHash TableDesignMatrix+1frequency 56.8
- Search a 2D Matrix IImediumArrayBinary SearchDivide and ConquerMatrixfrequency 56.8
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.