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
- Binary Tree Zigzag Level Order TraversalmediumTreeBreadth-First SearchBinary Treefrequency 55.5
- LFU CachehardHash TableLinked ListDesignDoubly-Linked Listfrequency 55.5
- Set Matrix ZeroesmediumArrayHash TableMatrixfrequency 55.5
- Two Sum II - Input Array Is SortedmediumArrayTwo PointersBinary Searchfrequency 55.5
- First Unique Character in a StringeasyHash TableStringQueueCountingfrequency 55.2
- Find the Index of the First Occurrence in a StringeasyTwo PointersStringString MatchingZ Algorithm+2frequency 55.0
- String CompressionmediumTwo PointersStringfrequency 55.0
- Next Greater Element IeasyArrayHash TableStackMonotonic Stackfrequency 54.7
- Binary Tree Level Order TraversalmediumTreeBreadth-First SearchBinary Treefrequency 54.4
- Missing NumbereasyArrayHash TableMathBinary Search+2frequency 54.4
- Next Greater Element IImediumArrayStackMonotonic Stackfrequency 54.1
- Reorder ListmediumLinked ListTwo PointersStackRecursionfrequency 54.1
- Gas StationmediumArrayGreedyfrequency 53.8
- Maximum Product SubarraymediumArrayDynamic Programmingfrequency 53.8
- String to Integer (atoi)mediumStringfrequency 53.8
- Pow(x, n)mediumMathRecursionfrequency 53.6
- Regular Expression MatchinghardStringDynamic ProgrammingRecursionfrequency 53.6
- Valid PalindromeeasyTwo PointersStringfrequency 53.6
- Word Search IIhardArrayStringBacktrackingTrie+1frequency 53.6
- CandyhardArrayGreedyfrequency 53.3
- Odd Even Linked ListmediumLinked Listfrequency 53.3
- Concatenated WordshardArrayStringDynamic ProgrammingDepth-First Search+2frequency 53.0
- Flood FilleasyArrayDepth-First SearchBreadth-First SearchMatrixfrequency 53.0
- Combination SummediumArrayBacktrackingfrequency 52.7
- Edit DistancemediumStringDynamic Programmingfrequency 52.7
- Longest Increasing SubsequencemediumArrayBinary SearchDynamic ProgrammingLongest Increasing Subsequencefrequency 52.7
- Remove Nth Node From End of ListmediumLinked ListTwo Pointersfrequency 52.7
- Diameter of Binary TreeeasyTreeDepth-First SearchBinary TreeDP on Treesfrequency 52.4
- Integer to RomanmediumHash TableMathStringfrequency 52.4
- Split Array Largest SumhardArrayBinary SearchDynamic ProgrammingGreedy+1frequency 52.4
- Validate Binary Search TreemediumTreeDepth-First SearchBinary Search TreeBinary Treefrequency 52.4
- Partition Equal Subset SummediumArrayDynamic ProgrammingKnapsack Problem0-1 Knapsackfrequency 52.0
- Basic CalculatorhardMathStringStackRecursionfrequency 51.7
- 3Sum ClosestmediumArrayTwo PointersSortingfrequency 51.4
- Largest NumbermediumArrayStringGreedySortingfrequency 51.4
- Linked List CycleeasyHash TableLinked ListTwo PointersFloyd's Cycle Finding Algorithmfrequency 51.4
- Max Consecutive OneseasyArrayfrequency 51.4
- Maximum Profit in Job SchedulinghardArrayBinary SearchDynamic ProgrammingSortingfrequency 51.4
- Middle of the Linked ListeasyLinked ListTwo Pointersfrequency 51.4
- Combine Two TableseasyDatabasefrequency 51.1
- Fibonacci NumbereasyMathDynamic ProgrammingRecursionMemoizationfrequency 51.1
- Intersection of Two ArrayseasyArrayHash TableTwo PointersBinary Search+1frequency 51.1
- Reverse Words in a StringmediumTwo PointersStringfrequency 51.1
- Happy NumbereasyHash TableMathTwo PointersFloyd's Cycle Finding Algorithmfrequency 50.7
- Number of ProvincesmediumDepth-First SearchBreadth-First SearchUnion-FindGraph Theoryfrequency 50.7
- Search a 2D Matrix IImediumArrayBinary SearchDivide and ConquerMatrixfrequency 50.7
- Sum of Subarray MinimumsmediumArrayDynamic ProgrammingStackMonotonic Stackfrequency 50.7
- Word Break IIhardArrayHash TableStringDynamic Programming+3frequency 50.7
- Add BinaryeasyMathStringBit ManipulationSimulationfrequency 50.4
- Palindrome PartitioningmediumStringDynamic ProgrammingBacktrackingfrequency 50.4
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.