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
- Valid Parenthesis StringmediumStringDynamic ProgrammingStackGreedy+111 companies
- Number of Visible People in a QueuehardArrayStackMonotonic Stack11 companies
- Employee Free TimehardArraySweep LineSortingHeap (Priority Queue)11 companies
- Minimum Path SummediumArrayDynamic ProgrammingMatrix11 companies
- First Missing PositivehardArrayHash Table11 companies
- Longest Repeating Character ReplacementmediumHash TableStringSliding Window11 companies
- Search a 2D MatrixmediumArrayBinary SearchMatrix11 companies
- The MazemediumArrayDepth-First SearchBreadth-First SearchMatrix11 companies
- Minimum Size Subarray SummediumArrayBinary SearchSliding WindowPrefix Sum11 companies
- Capacity To Ship Packages Within D DaysmediumArrayBinary Search10 companies
- Longest String ChainmediumArrayHash TableTwo PointersString+210 companies
- Remove All Adjacent Duplicates in String IImediumStringStack10 companies
- Special Binary StringhardStringDivide and ConquerSorting10 companies
- Squares of a Sorted ArrayeasyArrayTwo PointersSorting10 companies
- Partition Equal Subset SummediumArrayDynamic ProgrammingKnapsack Problem0-1 Knapsack10 companies
- Number of 1 BitseasyDivide and ConquerBit Manipulation10 companies
- Vertical Order Traversal of a Binary TreehardHash TableTreeDepth-First SearchBreadth-First Search+210 companies
- Minimum Number of Taps to Open to Water a GardenhardArrayDynamic ProgrammingGreedy10 companies
- Reverse BitseasyDivide and ConquerBit Manipulation10 companies
- Intersection of Two Linked ListseasyHash TableLinked ListTwo Pointers10 companies
- Restore IP AddressesmediumStringBacktracking10 companies
- Insert IntervalmediumArray10 companies
- Insert Delete GetRandom O(1) - Duplicates allowedhardArrayHash TableMathDesign+110 companies
- Fizz BuzzeasyMathStringSimulation10 companies
- CandyhardArrayGreedy10 companies
- Best Time to Buy and Sell Stock IIIhardArrayDynamic Programming10 companies
- Decode WaysmediumStringDynamic Programming10 companies
- Split Array Largest SumhardArrayBinary SearchDynamic ProgrammingGreedy+110 companies
- Minimum Knight MovesmediumBreadth-First SearchHeuristic SearchBidirectional SearchA* Search10 companies
- Maximum Depth of Binary TreeeasyTreeDepth-First SearchBreadth-First SearchBinary Tree10 companies
- House Robber IIImediumDynamic ProgrammingTreeDepth-First SearchBinary Tree+110 companies
- Search a 2D Matrix IImediumArrayBinary SearchDivide and ConquerMatrix10 companies
- Subarrays with K Different IntegershardArrayHash TableSliding WindowCounting10 companies
- 4SummediumArrayTwo PointersSorting10 companies
- Reorder ListmediumLinked ListTwo PointersStackRecursion10 companies
- Longest Common SubsequencemediumStringDynamic ProgrammingLongest Common Subsequence10 companies
- Count PrimesmediumArrayMathEnumerationNumber Theory+310 companies
- Spiral Matrix IImediumArrayMatrixSimulation10 companies
- Permutation in StringmediumHash TableTwo PointersStringSliding Window10 companies
- Find Minimum in Rotated Sorted ArraymediumArrayBinary Search10 companies
- Binary Tree CamerashardDynamic ProgrammingTreeDepth-First SearchBinary Tree+19 companies
- Moving Average from Data StreameasyArrayDesignQueueData Stream9 companies
- Walls and GatesmediumArrayBreadth-First SearchMatrix9 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
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.