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
- Sum of Subarray MinimumsmediumArrayDynamic ProgrammingStackMonotonic Stackfrequency 29.5
- Top K Frequent WordsmediumArrayHash TableStringTrie+4frequency 29.5
- Valid Parenthesis StringmediumStringDynamic ProgrammingStackGreedy+1frequency 29.5
- Validate Binary Search TreemediumTreeDepth-First SearchBinary Search TreeBinary Treefrequency 29.5
- Word Search IIhardArrayStringBacktrackingTrie+1frequency 29.5
- 01 MatrixmediumArrayDynamic ProgrammingBreadth-First SearchMatrixfrequency 22.0
- All Nodes Distance K in Binary TreemediumHash TableTreeDepth-First SearchBreadth-First Search+1frequency 22.0
- All O`one Data StructurehardHash TableLinked ListDesignDoubly-Linked Listfrequency 22.0
- Assign CookieseasyArrayTwo PointersGreedySorting+1frequency 22.0
- Balanced Binary TreeeasyTreeDepth-First SearchBinary Treefrequency 22.0
- Basic Calculator IIIhardMathStringStackRecursionfrequency 22.0
- Binary SearcheasyArrayBinary Searchfrequency 22.0
- Binary Search Tree IteratormediumStackTreeDesignBinary Search Tree+2frequency 22.0
- Binary Tree Maximum Path SumhardDynamic ProgrammingTreeDepth-First SearchBinary Tree+1frequency 22.0
- Binary Tree Zigzag Level Order TraversalmediumTreeBreadth-First SearchBinary Treefrequency 22.0
- Building H2OmediumConcurrencyfrequency 22.0
- Can Place FlowerseasyArrayGreedyfrequency 22.0
- Clone GraphmediumHash TableDepth-First SearchBreadth-First SearchGraph Theoryfrequency 22.0
- Construct Binary Tree from Preorder and Postorder TraversalmediumArrayHash TableDivide and ConquerTree+1frequency 22.0
- Contains Duplicate IIeasyArrayHash TableSliding Windowfrequency 22.0
- Convert Object to JSON Stringmediumfrequency 22.0
- Convert Sorted List to Binary Search TreemediumLinked ListDivide and ConquerTreeBinary Search Tree+1frequency 22.0
- Count PrimesmediumArrayMathEnumerationNumber Theory+3frequency 22.0
- Counting BitseasyDynamic ProgrammingBit Manipulationfrequency 22.0
- Design Linked ListmediumLinked ListDesignfrequency 22.0
- Design TwittermediumHash TableLinked ListDesignHeap (Priority Queue)frequency 22.0
- Determine if Two Strings Are ClosemediumHash TableStringSortingCountingfrequency 22.0
- Diameter of Binary TreeeasyTreeDepth-First SearchBinary TreeDP on Treesfrequency 22.0
- Dot Product of Two Sparse VectorsmediumArrayHash TableTwo PointersDesign+1frequency 22.0
- Encode and Decode TinyURLmediumHash TableStringDesignHash Functionfrequency 22.0
- Evaluate DivisionmediumArrayStringDepth-First SearchBreadth-First Search+5frequency 22.0
- Exclusive Time of FunctionsmediumArrayStackfrequency 22.0
- Find Distance in a Binary TreemediumHash TableTreeDepth-First SearchBreadth-First Search+3frequency 22.0
- First Bad VersioneasyBinary SearchInteractivefrequency 22.0
- First Letter to Appear TwiceeasyHash TableStringBit ManipulationCountingfrequency 22.0
- First Missing PositivehardArrayHash Tablefrequency 22.0
- Goat LatineasyStringfrequency 22.0
- Guess the WordhardArrayMathStringMinimax+2frequency 22.0
- Image SmoothereasyArrayMatrixfrequency 22.0
- Implement Stack using QueueseasyStackDesignQueuefrequency 22.0
- Intersection of Three Sorted ArrayseasyArrayHash TableBinary SearchCountingfrequency 22.0
- Koko Eating BananasmediumArrayBinary Searchfrequency 22.0
- Largest Rectangle in HistogramhardArrayStackMonotonic StackRange Minimum/Maximum Queryfrequency 22.0
- Longest Common SubsequencemediumStringDynamic ProgrammingLongest Common Subsequencefrequency 22.0
- Longest Happy PrefixhardStringRolling HashString MatchingHash Function+2frequency 22.0
- Longest Repeating Character ReplacementmediumHash TableStringSliding Windowfrequency 22.0
- Max Area of IslandmediumArrayDepth-First SearchBreadth-First SearchUnion-Find+1frequency 22.0
- Max Chunks To Make SortedmediumArrayStackGreedySorting+1frequency 22.0
- Maximize Distance to Closest PersonmediumArrayfrequency 22.0
- Maximum Population YeareasyArrayCountingPrefix Sumfrequency 22.0
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.