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
3,110 questions · all time
- Fibonacci NumbereasyMathDynamic ProgrammingRecursionMemoization8 companies
- Ransom NoteeasyHash TableStringCounting8 companies
- Counting BitseasyDynamic ProgrammingBit Manipulation8 companies
- Implement Stack using QueueseasyStackDesignQueue8 companies
- Longest Palindromic SubsequencemediumStringDynamic Programming8 companies
- Two Sum II - Input Array Is SortedmediumArrayTwo PointersBinary Search8 companies
- Best Time to Buy and Sell Stock with Transaction FeemediumArrayDynamic ProgrammingGreedy8 companies
- Pacific Atlantic Water FlowmediumArrayDepth-First SearchBreadth-First SearchMatrix8 companies
- Swap Nodes in PairsmediumLinked ListRecursion8 companies
- Delete Node in a BSTmediumTreeBinary Search TreeBinary Tree8 companies
- Meeting RoomseasyArraySortingQuicksort8 companies
- Maximal RectanglehardArrayDynamic ProgrammingStackMatrix+18 companies
- Add Two Numbers IImediumLinked ListMathStack8 companies
- Product of the Last K NumbersmediumArrayMathDesignData Stream+18 companies
- H-IndexmediumArraySortingCounting Sort8 companies
- Coin Change IImediumArrayDynamic ProgrammingKnapsack ProblemComplete Knapsack8 companies
- Put Marbles in BagshardArrayGreedySortingHeap (Priority Queue)8 companies
- Best Time to Buy and Sell Stock IVhardArrayDynamic Programming8 companies
- Amount of Time for Binary Tree to Be InfectedmediumHash TableTreeDepth-First SearchBreadth-First Search+18 companies
- Rearranging FruitshardArrayHash TableGreedySort8 companies
- Path SumeasyTreeDepth-First SearchBreadth-First SearchBinary Tree8 companies
- Swim in Rising WaterhardArrayBinary SearchDepth-First SearchBreadth-First Search+58 companies
- Remove Duplicates from Sorted List IImediumLinked ListTwo Pointers8 companies
- Isomorphic StringseasyHash TableString7 companies
- Minimum Number of Steps to Make Two Strings AnagrammediumHash TableStringCounting7 companies
- Minimum Operations to Reduce an Integer to 0mediumDynamic ProgrammingGreedyBit Manipulation7 companies
- Partition Array Into Two Arrays to Minimize Sum DifferencehardArrayTwo PointersBinary SearchDynamic Programming+57 companies
- Permutation SequencehardMathRecursion7 companies
- Using a Robot to Print the Lexicographically Smallest StringmediumHash TableStringStackGreedy7 companies
- Restore the Array From Adjacent PairsmediumArrayHash TableDepth-First Search7 companies
- Design Authentication ManagermediumHash TableLinked ListDesignDoubly-Linked List7 companies
- Lowest Common Ancestor of a Binary Search TreemediumTreeDepth-First SearchBinary Search TreeBinary Tree+27 companies
- Remove All Occurrences of a SubstringmediumStringStackSimulation7 companies
- Number of Distinct IslandsmediumArrayHash TableDepth-First SearchBreadth-First Search+47 companies
- Expression Add OperatorshardMathStringBacktracking7 companies
- Encode and Decode StringsmediumArrayStringDesign7 companies
- Design Snake GamemediumArrayHash TableDesignQueue+17 companies
- Contains Duplicate IIIhardArraySliding WindowSortingBucket Sort+17 companies
- Remove Sub-Folders from the FilesystemmediumArrayStringDepth-First SearchTrie7 companies
- Repeated DNA SequencesmediumHash TableStringBit ManipulationSliding Window+47 companies
- Shortest Word DistanceeasyArrayString7 companies
- Combination Sum IVmediumArrayDynamic Programming7 companies
- Frog JumphardArrayDynamic Programming7 companies
- Unique Binary Search TreesmediumMathDynamic ProgrammingTreeBinary Search Tree+17 companies
- 24 GamehardArrayMathBacktracking7 companies
- Minimum Number of Refueling StopshardArrayDynamic ProgrammingGreedyHeap (Priority Queue)7 companies
- Flatten a Multilevel Doubly Linked ListmediumLinked ListDepth-First SearchDoubly-Linked List7 companies
- Add DigitseasyMathSimulationNumber Theory7 companies
- Delete Node in a Linked ListmediumLinked List7 companies
- Design SpreadsheetmediumArrayHash TableStringDesign+17 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.