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
2,011 questions at Amazon · all time
- Minimum Time to Activate StringmediumArrayBinary Searchfrequency 21.9
- Missing Element in Sorted ArraymediumArrayBinary Searchfrequency 21.9
- NPV QuerieseasyDatabasefrequency 21.9
- Number of Distinct AverageseasyArrayHash TableTwo PointersSortingfrequency 21.9
- Number of Good PairseasyArrayHash TableMathCountingfrequency 21.9
- Number of Steps to Reduce a Number in Binary Representation to OnemediumStringBit ManipulationSimulationfrequency 21.9
- Number of Zero-Filled SubarraysmediumArrayMathfrequency 21.9
- Optimal DivisionmediumArrayMathDynamic Programmingfrequency 21.9
- Parsing A Boolean ExpressionhardStringStackRecursionfrequency 21.9
- Prison Cells After N DaysmediumArrayHash TableMathBit Manipulation+1frequency 21.9
- Range Sum Query 2D - ImmutablemediumArrayDesignMatrixPrefix Sumfrequency 21.9
- Rank Transform of an ArrayeasyArrayHash TableSortingfrequency 21.9
- Replace Elements in an ArraymediumArrayHash TableSimulationfrequency 21.9
- Replace Non-Coprime Numbers in ArrayhardArrayMathStackNumber Theory+2frequency 21.9
- Replace Question Marks in String to Minimize Its ValuemediumHash TableStringGreedySorting+2frequency 21.9
- Restaurant GrowthmediumDatabasefrequency 21.9
- Sales by Day of the WeekhardDatabasefrequency 21.9
- Scramble StringhardStringDynamic Programmingfrequency 21.9
- Separate Black and White BallsmediumTwo PointersStringGreedyfrequency 21.9
- Shift 2D GrideasyArrayMatrixSimulationfrequency 21.9
- Split Array into Fibonacci SequencemediumStringBacktrackingfrequency 21.9
- String Matching in an ArrayeasyArrayStringString Matchingfrequency 21.9
- Sum of Beauty in the ArraymediumArrayfrequency 21.9
- Time Taken to Cross the DoorhardArrayQueueSimulationfrequency 21.9
- Total Sum of Interaction Cost in Tree GroupshardArrayTreeDepth-First Searchfrequency 21.9
- Transpose MatrixeasyArrayMatrixSimulationfrequency 21.9
- Valid Perfect SquareeasyMathBinary Searchfrequency 21.9
- Valid Word AbbreviationeasyTwo PointersStringfrequency 21.9
- Ad-Free SessionseasyDatabasefrequency 20.0
- Add Two Polynomials Represented as Linked ListsmediumLinked ListMathTwo Pointersfrequency 20.0
- All Valid Triplets That Can Represent a CountryeasyDatabasefrequency 20.0
- Append K Integers With Minimal SummediumArrayMathGreedySortingfrequency 20.0
- Armstrong NumbereasyMathfrequency 20.0
- Basic Calculator IIIhardMathStringStackRecursionfrequency 20.0
- Binary Tree Postorder TraversaleasyStackTreeDepth-First SearchBinary Treefrequency 20.0
- Build Binary Expression Tree From Infix ExpressionhardStringStackTreeBinary Treefrequency 20.0
- Clear DigitseasyStringStackSimulationfrequency 20.0
- Clone N-ary TreemediumHash TableTreeDepth-First SearchBreadth-First Searchfrequency 20.0
- Closest Leaf in a Binary TreemediumTreeDepth-First SearchBreadth-First SearchBinary Treefrequency 20.0
- Combination Sum IVmediumArrayDynamic Programmingfrequency 20.0
- Complex Number MultiplicationmediumMathStringSimulationfrequency 20.0
- Connecting Cities With Minimum CostmediumUnion-FindGraph TheoryHeap (Priority Queue)Minimum Spanning Treefrequency 20.0
- Construct Binary Tree from StringmediumStringStackTreeDepth-First Search+1frequency 20.0
- Continuous SubarraysmediumArrayQueueSliding WindowHeap (Priority Queue)+2frequency 20.0
- Count Beautiful Substrings IIhardHash TableMathStringNumber Theory+1frequency 20.0
- Count Number of Bad PairsmediumArrayHash TableMathCountingfrequency 20.0
- Count Number of Nice SubarraysmediumArrayHash TableMathSliding Window+1frequency 20.0
- Count Number of Special SubsequenceshardArrayDynamic Programmingfrequency 20.0
- Count Number of TeamsmediumArrayDynamic ProgrammingBinary Indexed TreeSegment Treefrequency 20.0
- Count Numbers With Unique Digits IIeasyHash TableMathDynamic Programmingfrequency 20.0
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.