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
1,399 questions at Meta · all time
- Create Hello World Functioneasyfrequency 54.7
- Missing RangeseasyArrayfrequency 54.7
- Check Completeness of a Binary TreemediumTreeBreadth-First SearchBinary Treefrequency 54.4
- Squares of a Sorted ArrayeasyArrayTwo PointersSortingfrequency 54.1
- Toeplitz MatrixeasyArrayMatrixfrequency 54.1
- Word BreakmediumArrayHash TableStringDynamic Programming+3frequency 54.1
- Alien DictionaryhardArrayStringDepth-First SearchBreadth-First Search+3frequency 53.4
- Meeting Rooms IImediumArrayTwo PointersGreedySorting+2frequency 53.4
- Product of Array Except SelfmediumArrayPrefix Sumfrequency 53.4
- Sliding Window MaximumhardArrayQueueSliding WindowHeap (Priority Queue)+2frequency 53.4
- Plus OneeasyArrayMathfrequency 53.1
- Rotate ImagemediumArrayMathMatrixfrequency 53.1
- Valid AnagrameasyHash TableStringSortingfrequency 53.1
- Count Nodes Equal to Average of SubtreemediumTreeDepth-First SearchBinary Treefrequency 52.7
- Decode StringmediumStringStackRecursionfrequency 52.0
- Binary Tree Maximum Path SumhardDynamic ProgrammingTreeDepth-First SearchBinary Tree+1frequency 51.7
- Longest Valid ParentheseshardStringDynamic ProgrammingStackBracket Sequencesfrequency 51.7
- Palindrome Linked ListeasyLinked ListTwo PointersStackRecursionfrequency 51.7
- Spiral MatrixmediumArrayMatrixSimulationfrequency 51.7
- Friends Of Appropriate AgesmediumArrayTwo PointersBinary SearchSortingfrequency 50.5
- Reverse Linked ListeasyLinked ListRecursionfrequency 50.5
- Strobogrammatic NumbereasyHash TableTwo PointersStringfrequency 50.5
- 3Sum ClosestmediumArrayTwo PointersSortingfrequency 50.1
- Add BinaryeasyMathStringBit ManipulationSimulationfrequency 50.1
- Jump GamemediumArrayDynamic ProgrammingGreedyfrequency 50.1
- Lowest Common Ancestor of a Binary Search TreemediumTreeDepth-First SearchBinary Search TreeBinary Tree+2frequency 50.1
- Pascal's TriangleeasyArrayDynamic Programmingfrequency 50.1
- Remove Invalid ParentheseshardStringBacktrackingBreadth-First Searchfrequency 50.1
- Find Median from Data StreamhardTwo PointersDesignSortingHeap (Priority Queue)+1frequency 49.7
- Insert Delete GetRandom O(1)mediumArrayHash TableMathDesign+1frequency 49.7
- Unique PathsmediumMathDynamic ProgrammingCombinatoricsfrequency 49.7
- 4SummediumArrayTwo PointersSortingfrequency 49.3
- Boundary of Binary TreemediumTreeDepth-First SearchBinary Treefrequency 49.3
- Can Place FlowerseasyArrayGreedyfrequency 49.3
- Coin ChangemediumArrayDynamic ProgrammingBreadth-First SearchKnapsack Problem+1frequency 49.3
- Design Tic-Tac-ToemediumArrayHash TableDesignMatrix+1frequency 49.3
- Multiply StringsmediumMathStringSimulationfrequency 49.3
- Populating Next Right Pointers in Each NodemediumLinked ListTreeDepth-First SearchBreadth-First Search+1frequency 48.8
- Regular Expression MatchinghardStringDynamic ProgrammingRecursionfrequency 48.8
- Basic CalculatorhardMathStringStackRecursionfrequency 48.4
- Binary Tree Level Order TraversalmediumTreeBreadth-First SearchBinary Treefrequency 48.0
- Find the Index of the First Occurrence in a StringeasyTwo PointersStringString MatchingZ Algorithm+2frequency 48.0
- Sqrt(x)easyMathBinary SearchNewton's Methodfrequency 48.0
- Battleships in a BoardmediumArrayDepth-First SearchMatrixfrequency 47.5
- Best Time to Buy and Sell Stock IImediumArrayDynamic ProgrammingGreedyfrequency 47.5
- Construct Binary Tree from StringmediumStringStackTreeDepth-First Search+1frequency 47.5
- Contains DuplicateeasyArrayHash TableSortingfrequency 47.5
- Maximum Average Subarray IeasyArraySliding Windowfrequency 47.5
- Remove ElementeasyArrayTwo Pointersfrequency 47.5
- Find K Closest ElementsmediumArrayTwo PointersBinary SearchSliding Window+2frequency 47.0
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.