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.
Solve on Callback
4 problems asked at Google — full prompts you can work right here.
Pair Sum in a Sorted Array
Algorithms & Data Structures · The two-pointer warm-up every loop still asks.
Merge Overlapping Intervals
Algorithms & Data Structures · Sort, then sweep — the pattern behind a dozen calendar problems.
Design a URL Shortener
System Design · The classic: encoding, storage, and redirects at scale.
Build a Counter
Frontend · The React warm-up: state, events, and a derived disable.
Asked on LeetCode
2,344 questions at Google · all time
- Two SumeasyArrayHash Tablefrequency 100.0
- Add Two NumbersmediumLinked ListMathRecursionfrequency 78.6
- Median of Two Sorted ArrayshardArrayBinary SearchDivide and Conquerfrequency 73.9
- Trapping Rain WaterhardArrayTwo PointersDynamic ProgrammingStack+1frequency 73.9
- Longest Common PrefixeasyArrayStringTriefrequency 73.2
- Palindrome NumbereasyMathfrequency 73.2
- Longest Substring Without Repeating CharactersmediumHash TableStringSliding Windowfrequency 72.5
- 3SummediumArrayTwo PointersSortingfrequency 72.3
- Best Time to Buy and Sell StockeasyArrayDynamic Programmingfrequency 71.7
- Merge Sorted ArrayeasyArrayTwo PointersSortingfrequency 71.4
- Longest Consecutive SequencemediumArrayHash TableUnion-Findfrequency 69.6
- Longest Palindromic SubstringmediumTwo PointersStringDynamic ProgrammingManacherfrequency 69.5
- Merge Strings AlternatelyeasyTwo PointersStringfrequency 69.5
- Create Hello World Functioneasyfrequency 69.4
- Container With Most WatermediumArrayTwo PointersGreedyfrequency 68.1
- Majority ElementeasyArrayHash TableDivide and ConquerSorting+2frequency 66.6
- Valid ParentheseseasyStringStackBracket Sequencesfrequency 66.4
- Recyclable and Low Fat ProductseasyDatabasefrequency 66.0
- Reverse IntegermediumMathfrequency 65.6
- Roman to IntegereasyHash TableMathStringfrequency 65.6
- Remove Duplicates from Sorted ArrayeasyArrayTwo Pointersfrequency 65.5
- Subarray Sum Equals KmediumArrayHash TablePrefix Sumfrequency 65.5
- Merge IntervalsmediumArraySortingQuicksortfrequency 65.4
- Number of IslandsmediumArrayDepth-First SearchBreadth-First SearchUnion-Find+1frequency 65.3
- Maximum SubarraymediumArrayDivide and ConquerDynamic Programmingfrequency 64.7
- Climbing StairseasyMathDynamic ProgrammingMemoizationfrequency 63.5
- Merge Two Sorted ListseasyLinked ListRecursionfrequency 61.8
- Generate ParenthesesmediumStringDynamic ProgrammingBacktrackingBracket Sequencesfrequency 61.4
- Next PermutationmediumArrayTwo Pointersfrequency 60.7
- Reverse Linked ListeasyLinked ListRecursionfrequency 59.3
- Spiral MatrixmediumArrayMatrixSimulationfrequency 59.0
- Meeting Rooms IImediumArrayTwo PointersGreedySorting+2frequency 58.8
- Concatenation of ArrayeasyArraySimulationfrequency 58.6
- Add Two IntegerseasyMathfrequency 58.5
- Decode StringmediumStringStackRecursionfrequency 58.3
- Move ZeroeseasyArrayTwo Pointersfrequency 58.3
- Koko Eating BananasmediumArrayBinary Searchfrequency 58.2
- Remove ElementeasyArrayTwo Pointersfrequency 57.9
- Search in Rotated Sorted ArraymediumArrayBinary Searchfrequency 57.9
- LRU CachemediumHash TableLinked ListDesignDoubly-Linked Listfrequency 57.6
- Split Array Largest SumhardArrayBinary SearchDynamic ProgrammingGreedy+1frequency 57.6
- Top K Frequent ElementsmediumArrayHash TableDivide and ConquerSorting+4frequency 57.6
- N-QueenshardArrayBacktrackingAlgorithm Xfrequency 57.4
- House RobbermediumArrayDynamic Programmingfrequency 57.2
- Letter Combinations of a Phone NumbermediumHash TableStringBacktrackingfrequency 57.2
- Valid AnagrameasyHash TableStringSortingfrequency 57.2
- 4SummediumArrayTwo PointersSortingfrequency 57.1
- Jump GamemediumArrayDynamic ProgrammingGreedyfrequency 57.1
- Pascal's TriangleeasyArrayDynamic Programmingfrequency 57.1
- Single NumbereasyArrayBit Manipulationfrequency 57.1
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.