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Citadel LeetCode Questions 2026

Browse LeetCode problems frequently asked by Citadel. Filter by difficulty and timeframe to focus your interview prep.

Last updated: 20 May 2026

ProblemDifficultyFrequencyTopics
Merge k Sorted ListsHARD
62.5%
Linked ListDivide and ConquerHeap (Priority Queue)Merge Sort
Sudoku SolverHARD
50%
ArrayHash TableBacktrackingMatrix
Combination SumMEDIUM
50%
ArrayBacktracking
PermutationsMEDIUM
50%
ArrayBacktracking
Longest String ChainMEDIUM
50%
ArrayHash TableTwo PointersStringDynamic ProgrammingSorting
Best Time to Buy and Sell StockEASY
87.5%
ArrayDynamic Programming
Best Time to Buy and Sell Stock IIIHARD
50%
ArrayDynamic Programming
Binary Tree Maximum Path SumHARD
62.5%
Dynamic ProgrammingTreeDepth-First SearchBinary Tree
LRU CacheMEDIUM
87.5%
Hash TableLinked ListDesignDoubly-Linked List
Evaluate Reverse Polish NotationMEDIUM
75%
ArrayMathStack
Number of IslandsMEDIUM
62.5%
ArrayDepth-First SearchBreadth-First SearchUnion-FindMatrix
Course ScheduleMEDIUM
50%
Depth-First SearchBreadth-First SearchGraph TheoryTopological Sort
Maximal SquareMEDIUM
50%
ArrayDynamic ProgrammingMatrix
Sliding Window MaximumHARD
100%
ArrayQueueSliding WindowHeap (Priority Queue)Monotonic Queue
Perfect SquaresMEDIUM
50%
MathDynamic ProgrammingBreadth-First Search
Find the Duplicate NumberMEDIUM
75%
ArrayTwo PointersBinary SearchBit Manipulation
Find Median from Data StreamHARD
87.5%
Two PointersDesignSortingHeap (Priority Queue)Data Stream
Serialize and Deserialize Binary TreeHARD
62.5%
StringTreeDepth-First SearchBreadth-First SearchDesignBinary Tree
Maximum Total Damage With Spell CastingMEDIUM
87.5%
ArrayHash TableTwo PointersBinary SearchDynamic ProgrammingSortingCounting
Search Suggestions SystemMEDIUM
50%
ArrayStringBinary SearchTrieSortingHeap (Priority Queue)

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