Problems
Callback's own problems and the LeetCode questions companies have been asking, in one place — pick a category, then filter by company, frequency, status, difficulty, topic, and language.
Asked on LeetCode
3,115 questions · all time
- Permutation in StringmediumHash TableTwo PointersStringSliding Window10 companies
- Binary Tree CamerashardDynamic ProgrammingTreeDepth-First SearchBinary Tree+19 companies
- Moving Average from Data StreameasyArrayDesignQueueData Stream9 companies
- Walls and GatesmediumArrayBreadth-First SearchMatrix9 companies
- Parallel Courses IIIhardArrayDynamic ProgrammingGraph TheoryTopological Sort+19 companies
- Design TwittermediumHash TableLinked ListDesignHeap (Priority Queue)9 companies
- Remove All Adjacent Duplicates In StringeasyStringStack9 companies
- Best Meeting PointhardArrayMathSortingMatrix9 companies
- Kth Smallest Element in a Sorted MatrixmediumArrayBinary SearchSortingHeap (Priority Queue)+19 companies
- The Skyline ProblemhardArrayDivide and ConquerBinary Indexed TreeSegment Tree+49 companies
- Validate IP AddressmediumString9 companies
- Binary Tree Vertical Order TraversalmediumHash TableTreeDepth-First SearchBreadth-First Search+29 companies
- Number of ProvincesmediumDepth-First SearchBreadth-First SearchUnion-FindGraph Theory9 companies
- Maximum Sum Circular SubarraymediumArrayDivide and ConquerDynamic ProgrammingQueue+19 companies
- Lowest Common Ancestor of a Binary Tree IIImediumHash TableTwo PointersTreeBinary Tree+29 companies
- Majority ElementeasyArrayHash TableDivide and ConquerSorting+29 companies
- Block Placement QuerieshardArrayBinary SearchBinary Indexed TreeSegment Tree+19 companies
- Binary Tree Right Side ViewmediumTreeDepth-First SearchBreadth-First SearchBinary Tree9 companies
- Find All Anagrams in a StringmediumHash TableStringSliding Window9 companies
- Kth Smallest Element in a BSTmediumTreeDepth-First SearchBinary Search TreeBinary Tree9 companies
- Reverse StringeasyTwo PointersString9 companies
- Find the CelebritymediumTwo PointersGraph TheoryInteractive9 companies
- Burst BalloonshardArrayDynamic Programming9 companies
- Minimum Cost For TicketsmediumArrayDynamic Programming9 companies
- MinesweepermediumArrayDepth-First SearchBreadth-First SearchMatrix9 companies
- HeatersmediumArrayTwo PointersBinary SearchSorting9 companies
- First Unique Character in a StringeasyHash TableStringQueueCounting9 companies
- Power of TwoeasyMathBit ManipulationRecursion9 companies
- Middle of the Linked ListeasyLinked ListTwo Pointers9 companies
- Palindrome Linked ListeasyLinked ListTwo PointersStackRecursion9 companies
- Reverse IntegermediumMath9 companies
- Can Place FlowerseasyArrayGreedy9 companies
- Contains Duplicate IIeasyArrayHash TableSliding Window9 companies
- N-QueenshardArrayBacktrackingAlgorithm X9 companies
- Unique Paths IImediumArrayDynamic ProgrammingMatrix9 companies
- Design File SystemmediumHash TableStringDesignTrie9 companies
- Range Sum Query 2D - ImmutablemediumArrayDesignMatrixPrefix Sum9 companies
- SubsetsmediumArrayBacktrackingBit Manipulation9 companies
- Remove Nth Node From End of ListmediumLinked ListTwo Pointers9 companies
- Maximum Product of Three NumberseasyArrayMathSorting9 companies
- Is SubsequenceeasyTwo PointersStringDynamic Programming9 companies
- Exclusive Time of FunctionsmediumArrayStack9 companies
- Sliding Window MedianhardArrayHash TableSliding WindowHeap (Priority Queue)+19 companies
- Basic Calculator IIIhardMathStringStackRecursion9 companies
- Fruit Into BasketsmediumArrayHash TableSliding Window9 companies
- Largest NumbermediumArrayStringGreedySorting9 companies
- Add StringseasyMathStringSimulation9 companies
- Robot Bounded In CirclemediumMathStringSimulation9 companies
- Single NumbereasyArrayBit Manipulation9 companies
- Find Pivot IndexeasyArrayPrefix Sum9 companies
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.