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
- Best Time to Buy and Sell Stock with Transaction FeemediumArrayDynamic ProgrammingGreedyfrequency 55.0
- Compare Version NumbersmediumTwo PointersStringfrequency 55.0
- Find the Index of the First Occurrence in a StringeasyTwo PointersStringString MatchingZ Algorithm+2frequency 55.0
- Implement Trie (Prefix Tree)mediumHash TableStringDesignTriefrequency 55.0
- Number of 1 BitseasyDivide and ConquerBit Manipulationfrequency 55.0
- Peeking IteratormediumArrayDesignIteratorfrequency 55.0
- Ransom NoteeasyHash TableStringCountingfrequency 55.0
- String CompressionmediumTwo PointersStringfrequency 55.0
- Binary Tree Level Order TraversalmediumTreeBreadth-First SearchBinary Treefrequency 53.1
- Calculate Score After Performing InstructionsmediumArrayHash TableStringSimulationfrequency 53.1
- Design HashMapeasyArrayHash TableLinked ListDesign+1frequency 53.1
- Find Servers That Handled Most Number of RequestshardArrayHeap (Priority Queue)SimulationOrdered Setfrequency 53.1
- First Unique Character in a StringeasyHash TableStringQueueCountingfrequency 53.1
- Longest Consecutive SequencemediumArrayHash TableUnion-Findfrequency 53.1
- Regular Expression MatchinghardStringDynamic ProgrammingRecursionfrequency 53.1
- Remove Duplicates from Sorted ArrayeasyArrayTwo Pointersfrequency 53.1
- Array NestingmediumArrayDepth-First Searchfrequency 51.0
- Delete Node in a Linked ListmediumLinked Listfrequency 51.0
- Flatten Nested List IteratormediumStackTreeDepth-First SearchDesign+2frequency 51.0
- Longest Palindromic SubstringmediumTwo PointersStringDynamic ProgrammingManacherfrequency 51.0
- Max Points on a LinehardArrayHash TableMathGeometry+2frequency 51.0
- Number of Squareful ArrayshardArrayHash TableMathDynamic Programming+3frequency 51.0
- Pascal's TriangleeasyArrayDynamic Programmingfrequency 51.0
- Remove Nth Node From End of ListmediumLinked ListTwo Pointersfrequency 51.0
- Serialize and Deserialize Binary TreehardStringTreeDepth-First SearchBreadth-First Search+2frequency 51.0
- Sqrt(x)easyMathBinary SearchNewton's Methodfrequency 51.0
- Binary Tree PathseasyStringBacktrackingTreeDepth-First Search+1frequency 48.7
- Count the Number of Incremovable Subarrays IeasyArrayTwo PointersBinary SearchEnumerationfrequency 48.7
- Count the Number of Incremovable Subarrays IIhardArrayTwo PointersBinary Searchfrequency 48.7
- Decode StringmediumStringStackRecursionfrequency 48.7
- Find the Grid of Region AveragemediumArrayMatrixfrequency 48.7
- Implement Queue using StackseasyStackDesignQueuefrequency 48.7
- LFU CachehardHash TableLinked ListDesignDoubly-Linked Listfrequency 48.7
- Letter Combinations of a Phone NumbermediumHash TableStringBacktrackingfrequency 48.7
- Maximal SquaremediumArrayDynamic ProgrammingMatrixfrequency 48.7
- Maximum Depth of Binary TreeeasyTreeDepth-First SearchBreadth-First SearchBinary Treefrequency 48.7
- Maximum Rows Covered by ColumnsmediumArrayBacktrackingBit ManipulationMatrix+1frequency 48.7
- Number of Pairs of Strings With Concatenation Equal to TargetmediumArrayHash TableStringCountingfrequency 48.7
- Remove All Adjacent Duplicates In StringeasyStringStackfrequency 48.7
- Search in Rotated Sorted ArraymediumArrayBinary Searchfrequency 48.7
- Task SchedulermediumArrayHash TableGreedySorting+2frequency 48.7
- Container With Most WatermediumArrayTwo PointersGreedyfrequency 46.0
- Fibonacci NumbereasyMathDynamic ProgrammingRecursionMemoizationfrequency 46.0
- Find K Closest ElementsmediumArrayTwo PointersBinary SearchSliding Window+2frequency 46.0
- Find Winner on a Tic Tac Toe GameeasyArrayHash TableMatrixSimulationfrequency 46.0
- Flood FilleasyArrayDepth-First SearchBreadth-First SearchMatrixfrequency 46.0
- Generate ParenthesesmediumStringDynamic ProgrammingBacktrackingBracket Sequencesfrequency 46.0
- Integer to English WordshardMathStringRecursionfrequency 46.0
- Jump GamemediumArrayDynamic ProgrammingGreedyfrequency 46.0
- Meeting RoomseasyArraySortingQuicksortfrequency 46.0
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.