Appendix: Repo Coverage Index

Every file in src/main/kotlin/ — 667 files — mapped to this book.

Legend: → covered by a full page · variant of an alternative/duplicate implementation documented elsewhere · support a helper/non-problem file.

`GenerateReadme.kt/` (1 files)

File	Coverage
`GenerateReadme.kt`	support / non-problem

`Main.kt/` (1 files)

File	Coverage
`Main.kt`	support / non-problem

`array/` (115 files)

File	Coverage
`CheckkIfArrayIsSortedAndRotated.kt`	→ find minimum in rotated sorted array
`ClosestSubsequenceSum.kt`	→ closest subsequence sum
`Combinations.kt`	→ combinations
`NextGreaterElement_III.kt`	→ next greater element ii
`NextPermutation.kt`	→ next permutation
`NextPermutationShorter.kt`	→ next permutation
`PermutationHardFollowup.kt`	variant of next permutation
`Permutation_II.kt`	→ next permutation
`Permutation_II_Backtracking.kt`	→ next permutation
`Permutation_II_NarayanPandita.kt`	variant of next permutation
`Permutations.kt`	→ permutations
`Subsets.kt`	→ partition to k equal sum subsets
`Subsets_II.kt`	→ partition to k equal sum subsets
`practice.kt`	support / non-problem
`DiagonalTraverse.kt`	→ diagonal traverse
`DiagonalTraverse_II.kt`	→ diagonal traverse
`InsertInterval.kt`	→ insert interval
`MergeIntervals.kt`	→ merge intervals
`MergeSortedArray.kt`	→ merge sorted array
`MissingRanges.kt`	→ first missing positive
`MoveZeroes.kt`	→ move zeroes
`RemoveElement.kt`	→ find peak element
`RotateImage.kt`	→ rotate image
`SearchA2dMatrix_II.kt`	→ search a 2d matrix
`SetMatrixZeroes.kt`	→ set matrix zeroes
`ShortestPathInBinaryMatrix.kt`	support / non-problem
`SignOfTheProductOfAnArray.kt`	→ product of array except self
`SpiralMatrix.kt`	→ spiral matrix
`SpiralMatrix_II.kt`	→ spiral matrix
`ToeplitzMatrix.kt`	→ search a 2d matrix
`TransposeMatrix.kt`	→ search a 2d matrix
`CombinationSum.kt`	→ combination sum
`CombinationSum3.kt`	→ combination sum
`CombinationSum_II.kt`	→ combination sum
`NQueen.kt`	→ n-queens
`FindTheDuplicateNumber.kt`	→ find the duplicate number
`NestedListWeightedSum.kt`	→ flatten nested list iterator
`BurstBallonsClean.kt`	variant of minimum number of arrows to burst balloons
`BurstBaloons.kt`	→ minimum number of arrows to burst balloons
`CoinChange.kt`	→ coin change
`CoinChangeBFS.kt`	→ coin change
`CoinChangeBottomUp.kt`	→ coin change
`CoinChange_II.kt`	→ coin change
`CoinChange_II_BottomUp.kt`	→ coin change
`HouseRobber.kt`	→ house robber
`HouseRobber_II.kt`	→ house robber
`KadensAlgorithm.kt`	→ maximum subarray (Kadane’s algorithm)
`LongestCommonSubarray.kt`	→ longest common prefix
`LongestIncreasingSequenceInAMatrix.kt`	→ longest consecutive sequence
`LongestIncreasingSubsequence.kt`	→ longest increasing subsequence
`MaximalSquare.kt`	→ maximal square
`MaximumSumOfNonAdjacentElements.kt`	variant of binary tree maximum path sum
`MaximumSumSubArray.kt`	→ binary tree maximum path sum
`MinCostClimbingStaris.kt`	→ min cost to connect all points
`MinimumNumberofIncrementsSubarraysFormaTargetArray.kt`	variant of find minimum in rotated sorted array
`MinimumPathSum.kt`	→ binary tree maximum path sum
`PartitionArrayIntoTwoArrayToMinimuzeSumDifference.kt`	variant of partition equal subset sum
`SplitArrayLargestSum.kt`	variant of binary tree maximum path sum
`StoneGame.kt`	→ jump game
`TargetSum.kt`	→ binary tree maximum path sum
`CanPlaceFlowers.kt`	→ can place flowers
`ContainerWithMostWater.kt`	→ container with most water
`IncreasingTripletSequence.kt`	variant of longest consecutive sequence
`KItemsWithMaximumSum.kt`	→ binary tree maximum path sum
`MInimumNumberOfArrowsRequiredToBurstBallons.kt`	→ minimum number of arrows to burst balloons
`MaximumDistanceInArray.kt`	variant of binary tree maximum path sum
`MaximumSwap.kt`	→ binary tree maximum path sum
`MergeOverlappingIntervals.kt`	→ merge intervals
`MinimumNumberOfTapsToWaterGarden.kt`	variant of minimum number of arrows to burst balloons
`MinimumNumberofSwapstoMaketheStringBalanced.kt`	→ minimum number of swaps to make the string balanced
`NonOverlappingIntervals.kt`	→ non-overlapping intervals
`ContainsDuplicate_II.kt`	→ contains duplicate ii
`DegreeOfAnArray.kt`	→ find minimum in rotated sorted array
`DivideArrayIntoEqualPairs.kt`	variant of find minimum in rotated sorted array
`EqualRowAndColumnPairs.kt`	→ equal row and column pairs
`FindDifferenceOfTwoArrays.kt`	→ median of two sorted arrays
`FindMissingPositive.kt`	→ first missing positive
`FirstMissingPositive.kt`	→ first missing positive
`IntegerToEnglishWords.kt`	variant of count words with a given prefix
`LongestConsecutiveSequence.kt`	→ longest consecutive sequence
`MaxNUmWithKSumPairs.kt`	variant of max consecutive ones iii
`NumberOfGoodPairs.kt`	variant of find the duplicate number
`RankTransformOfAnArray.kt`	variant of find minimum in rotated sorted array
`SetMismatch.kt`	→ set matrix zeroes
`SnapshotArray.kt`	→ find minimum in rotated sorted array
`UniqueNumberOfOccurences.kt`	variant of find the duplicate number
`ValidSudoku.kt`	→ valid sudoku
`2DPrefixSumImmutable.kt`	variant of binary tree maximum path sum
`ContiguousArray.kt`	→ find minimum in rotated sorted array
`ContinuousSubarraySum.kt`	→ minimum size subarray sum
`FIndTheHighestAltitute.kt`	variant of find first and last position of target
`FindPivotIndex.kt`	→ find the index of the first occurrence (kmp)
`Minimum NumberofOperationstoMoveAllBallstoEachBox.kt`	→ minimum operations to move all balls
`NumberOfZeroFilledSubArrays.kt`	→ number of zero-filled subarrays
`ProductOfArrayExceptSelf.kt`	→ product of array except self
`SubArrayProductLessThanK.kt`	→ product of array except self
`SubArraySumEqualsToK.kt`	→ subarray sum equals k
`SubArraySumsDivisibleByK.kt`	→ subarray sums divisible by k
`ZeroArrayTransformation_I.kt`	variant of find minimum in rotated sorted array
`RandomPickIndex.kt`	→ random pick with weight
`MeetingScheduler.kt`	→ meeting rooms
`SortColors.kt`	→ sort colors
`SquaresOfASortedArray.kt`	variant of find minimum in rotated sorted array
`MaximumPopulationYear.kt`	variant of binary tree maximum path sum
`4Sum.kt`	→ binary tree maximum path sum
`IntervalListIntersection.kt`	variant of flatten nested list iterator
`LongestMountainInArray.kt`	→ peak index in a mountain array
`NumberOfArithmaticTriplet.kt`	variant of find the duplicate number
`RemoveDuplicateElementsFromSortedArray.kt`	variant of contains duplicate ii
`RemoveDuplicateElementsFromSortedArray_II.kt`	variant of contains duplicate ii
`RotateArray.kt`	→ find minimum in rotated sorted array
`ThreeSum.kt`	→ three sum
`ThreeSumClosest.kt`	→ closest subsequence sum
`TrappingRainWater.kt`	→ trapping rain water
`TwoSum_II.kt`	→ two sum

`autopilot/` (1 files)

File	Coverage
`H1bAutoPilotStressAnxietyAlgorithm.kt`	support / non-problem

`backtracking/` (12 files)

File	Coverage
`ExpressionAndAddOperators.kt`	variant of add two numbers
`ExpressionAndAddOperatorsOptimized.kt`	variant of add two numbers
`NQueen.kt`	→ n-queens
`NQueenOptimized.kt`	variant of n-queens (optimized)
`NQueen_II.kt`	→ n-queens ii
`PalindromePartitioning.kt`	→ palindrome partitioning
`PartitionToKEqualSumSubsets.kt`	→ partition to k equal sum subsets
`PathWithMaximumGold.kt`	→ binary tree maximum path sum
`RestoreIPAddresses.kt`	→ restore ip addresses
`Strobogrammatic_Number_II.kt`	→ find the duplicate number
`SudokuSolver.kt`	→ sudoku solver
`SudokuSolverSet.kt`	→ sudoku solver

`binarysearch/` (22 files)

File	Coverage
`ApartmentHunting.kt`	→ apartment hunting
`CapacityToShipPackageWithinDDays.kt`	→ capacity to ship packages within d days
`ClosestSebsequenceSum.kt`	→ closest subsequence sum
`FindFirstAndLastPosition.kt`	→ find first and last position of target
`FindKClosestElements.kt`	→ find k closest elements
`FindMinimumInRotatedSortedArray.kt`	→ find minimum in rotated sorted array
`FindPeakElement.kt`	→ find peak element
`FindPeakElementBetterSolution.kt`	→ find peak element
`FirstBadVersion.kt`	→ first bad version
`GuessNumberHigherOrLower.kt`	→ guess number higher or lower
`HouseRobber_IV.kt`	→ house robber
`KThMissingPositiveNumber.kt`	→ kth missing positive number
`KokoEatingBanana.kt`	→ koko eating bananas
`MedianOfTwoSortedARrays.kt`	→ median of two sorted arrays
`PeakIndexInMountainArray.kt`	→ peak index in a mountain array
`RandomPickWithWeight.kt`	→ random pick with weight
`SearchA2dMatrix.kt`	→ search a 2d matrix
`SearchInRotatedArray_II.kt`	→ search in rotated sorted array
`SearchInRotatedSortedArray.kt`	→ search in rotated sorted array
`SearchInsertionPosition.kt`	→ search insert position
`SingleElementInASortedArray.kt`	→ single element in a sorted array
`ValleyElement.kt`	→ valley element

`bitset/` (10 files)

File	Coverage
`FirstLetterToAppearTwice.kt`	variant of find first and last position of target
`LongestNiceSubarray.kt`	variant of longest common prefix
`MaximumXorOfTwoNumsInArray.kt`	→ maximum xor of two numbers
`Number of Steps to ReduceaANumberInBinaryRepresentationtoOne.kt`	→ number of steps to reduce a number in binary
`NumberOfOneBits.kt`	→ number of 1 bits
`ReverseBits.kt`	→ reverse bits
`SingleNumber.kt`	→ single number
`SingleNumber3.kt`	→ single element in a sorted array
`SmallestNumberWithAllSetBits.kt`	→ smallest number with all set bits
`SumOfAllSubsetXorTotal.kt`	→ sum of all subset xor totals

`cache/` (11 files)

File	Coverage
`LFUCache.kt`	→ lfu cache
`LFUCacheGigaCHAD.kt`	variant of lfu cache
`LRUCache.kt`	→ lru cache
`LRUCacheBetter.kt`	variant of lru cache
`LRUCacheLinkedList.kt`	→ linked list cycle
`LRUCleanAf.kt`	variant of lru cache
`LfuCacheNobodyDoesItBetter.kt`	variant of lfu cache
`LruCacheBruceLee.kt`	→ lru cache
`LruCacheFuckYeah.kt`	→ lru cache
`LruCacheNobodyDoesItBetter.kt`	variant of lru cache
`ThreadSafeLruCache.kt`	→ thread-safe sharded lru

`commons/` (3 files)

File	Coverage
`APIEndPoints.kt`	support / non-problem
`AlpacaWebSocketFactory.kt`	support / non-problem
`FileWriter.kt`	support / non-problem

`design/` (2 files)

File	Coverage
`PeekingIterator.kt`	→ peeking iterator
`SelfDoubtSimulation.kt`	support / non-problem

`disjointset/` (7 files)

File	Coverage
`AccountMerge.kt`	→ merge intervals
`DynamicConnectivity.kt`	→ dynamic connectivity
`NumberOfIsland_II.kt`	→ find the duplicate number
`NumerOfIsland_II_Optimized.kt`	→ max area of island
`PowerGridMaintainance.kt`	support / non-problem
`TheEarliestMomentEveryoneBecameFriends.kt`	→ the earliest moment everyone became friends
`UnionFind.kt`	→ find first and last position of target

`dynamic_programming/` (12 files)

File	Coverage
`01Knapsack.kt`	→ 0/1 knapsack
`ClosestSubsequenceSum.kt`	→ closest subsequence sum
`FrogJump.kt`	→ frog jump
`FrogJumpTopDown.kt`	→ frog jump
`MaximumProductSubarray.kt`	→ maximum product subarray
`MaximumProfitInJobScheduling.kt`	→ maximum profit in job scheduling
`MinimumCostToCutAStick.kt`	→ minimum cost to cut a stick
`MinimumCostToMergeStones.kt`	→ minimum cost to merge stones
`MinimumCostToMergeStones_Intuition.kt`	→ minimum cost to merge stones
`PartitionEqualSubsetSum.kt`	→ partition equal subset sum
`SuperEggDropping.kt`	→ super egg drop
`UnboundedKnapsack.kt`	→ unbounded knapsack

`facebook/` (2 files)

File	Coverage
`FindMinimumTicketPrice.kt`	→ find minimum in rotated sorted array
`SecondGreatestNumber.kt`	support / non-problem

`geo/` (4 files)

File	Coverage
`KDTreeExample.kt`	→ kd-tree
`ConstructQuadTree.kt`	→ construct tree from preorder and inorder
`QuadTree.kt`	→ binary tree inorder traversal (iterative)
`QuadTreeUsagePlaceFinding.kt`	support / non-problem

`google/` (14 files)

File	Coverage
`CountNumberOfWaysToPickKCoinsSumDivisibleByM.kt`	→ count ways to pick k coins divisible by m
`CourseWithSemesterConstraint.kt`	variant of course schedule ii
`GoogleCheatSeetDeepSeekDeekThinkEdition.kt`	support / non-problem
`GoogleCheatSheat.kt`	support / non-problem
`GoogleCheatSheet_II.kt`	support / non-problem
`GoogleCheatSheet_III.kt`	support / non-problem
`GoogleCheatSheet_IV.kt`	support / non-problem
`GooglrCheatSheetGraphEdition.kt`	support / non-problem
`HandsOnCollectionsPLayground.kt`	support / non-problem
`LargestSquareAreaInMatrix.kt`	variant of kth largest element
`MInDifferenceBetweenTotalSums.kt`	variant of min cost to connect all points
`MinimumTimeToFinishBuildByKWorkers.kt`	→ minimum time to collect all apples
`ShuffleWithRandomness.kt`	→ shuffle an array
`SongShuffle.kt`	→ shuffle an array

`graph/` (77 files)

File	Coverage
`BusRoutes.kt`	→ reorder routes to city zero
`CalculateGraphDiameter.kt`	variant of clone graph
`ChromaticNumber.kt`	→ find the duplicate number
`ChromaticNumberOptimized.kt`	variant of find the duplicate number
`CloneGraph.kt`	→ clone graph
`CourseSchedule_II_Idiomatic.kt`	→ course schedule ii
`DiameterOfBinaryTree.kt`	→ diameter of binary tree
`EvalualteDivisions.kt`	→ evaluate division
`HouseRobber3.kt`	→ house robber
`IsBipartileBFSFunctional.kt`	variant of is graph bipartite (BFS functional version)
`IsBipartileGraph.kt`	→ clone graph
`IsBipartileGraphDfs.kt`	variant of clone graph
`LargeScaleCourseSchedule.kt`	→ course schedule ii
`MaximumPathQualityOfAGraph.kt`	→ binary tree maximum path sum
`MinimumGeneticMutations.kt`	variant of find minimum in rotated sorted array
`NColoringGraph.kt`	→ clone graph
`NColoringGreedy.kt`	→ n-coloring greedy
`ParallelCourses_II_FunctionalProgramming.kt`	support / non-problem
`ReorderRoutesToMakeAllPathsLeadToCityZero.kt`	support / non-problem
`WordLadder.kt`	→ word ladder
`WordLadder_II.kt`	→ word ladder
`WordLadder_II_FinalCutPro.kt`	variant of word ladder
`WordLadder_II_clean.kt`	→ word ladder
`CriticalConnectionsInANetwork.kt`	→ critical connections in a network
`CriticalConnectionsInANetworkShortCode.kt`	variant of critical connections in a network
`FindArticulationPoints.kt`	variant of count rectangles formed by points
`BinarySearchTreeToGreaterSumTree.kt`	→ binary tree maximum path sum
`RangeSumOfBST.kt`	variant of binary tree maximum path sum
`FindConnectedComponents.kt`	→ strongly connected components
`BFSCycleDetection.kt`	variant of course schedule ii (Kahn’s BFS cycle detection)
`CourseSchedule.kt`	→ course schedule ii
`CourseSchedule_II.kt`	→ course schedule ii
`FindLengthOfLongestCycle.kt`	variant of find first and last position of target
`ParallelCourses.kt`	support / non-problem
`BellmanFordAlgorithm.kt`	→ bellman-ford
`CheapestFlightsWithinKStops.kt`	→ cheapest flights with k stops
`CheapestFlightsWithinKStopsBellman.kt`	→ cheapest flights with k stops
`FloydWarshallAlgorithm.kt`	→ floyd-warshall
`MaximumVacationDays.kt`	variant of binary tree maximum path sum
`ParallelCourses_II.kt`	support / non-problem
`ParallelCourses_II_Recursive.kt`	support / non-problem
`SocialNetworkOperations.kt`	variant of critical connections in a network
`CrackingTheSafe.kt`	→ find peak element (safe boundaries)
`FindEulerianCircuit.kt`	variant of find first and last position of target
`Theory.kt`	support / non-problem
`ReconstructItenary.kt`	→ reconstruct itinerary
`ValidArrangementOfPairs.kt`	variant of longest valid parentheses
`ValidArrangementOfPairsRecursive.kt`	variant of longest valid parentheses
`BipartileMatching.kt`	→ maximum bipartite matching
`EdmondsKarp.kt`	→ max flow (edmonds-karp)
`EdmondsKarpAdjacencyList.kt`	→ max flow (edmonds-karp)
`EdmondsKarpAnother.kt`	→ max flow (edmonds-karp)
`EdmondsKarpImpovised.kt`	→ max flow (edmonds-karp)
`MaxFlowEdmondsKarp.kt`	→ max flow (edmonds-karp)
`MaximumBipartileJobMatching.kt`	→ maximum bipartite matching
`CheapestFlightWithKStops.kt`	variant of cheapest flights with k stops
`CheapestFlightsWithKStops.kt`	→ cheapest flights with k stops
`DonaldTrumpAlgorithm.kt`	support / non-problem
`NetworkDelayTime.kt`	→ network delay time
`TheMaze_III.kt`	→ max consecutive ones iii
`FindRedundentConnections.kt`	variant of critical connections in a network
`OptimizeWaterDistributionInAVillage.kt`	variant of container with most water
`PrimsAlgorithm.kt`	→ min cost to connect all points (prim’s)
`PrimsShorter.kt`	→ min cost to connect all points (prim’s)
`Kosaraju.kt`	variant of strongly connected components (Kosaraju’s algorithm)
`Tarjans.kt`	variant of strongly connected components (Tarjan’s algorithm)
`AlienDictionary.kt`	→ alien dictionary
`AlienDictionary_BFS.kt`	→ alien dictionary
`ApplySubstitutions.kt`	→ apply substitutions
`CourseSchedule_II.kt`	→ course schedule ii
`CourseSchedule_II_BFS.kt`	→ course schedule ii
`ProteinFolding.kt`	support / non-problem
`ShortestPathVisitingAllNodes.kt`	support / non-problem
`TSPHelpKarp.kt`	→ find the index of the first occurrence (rabin-karp)
`TravellingSalesPersonTopDownDP.kt`	variant of travelling salesman (held-karp) (top-down DP)
`TravellingSalesmanRecursiveDP.kt`	→ travelling salesman (held-karp)
`TravellingSalespersonProblemBruteforceMatrix.kt`	variant of travelling salesman (held-karp) (brute force)

`greedy/` (17 files)

File	Coverage
`CarFleet.kt`	→ car fleet
`DestroyingAsteroids.kt`	→ destroying asteroids
`JumpGame.kt`	→ jump game
`JumpGame_II.kt`	→ jump game
`MInimumCostHomecomingOfARobot.kt`	→ minimum cost to cut a stick
`MaxChuncksToMakeSorted_II.kt`	variant of max consecutive ones iii
`MaxProfiAssigningWork.kt`	variant of max consecutive ones iii
`MaximumValueOfAnOrderedTriplet_II.kt`	variant of binary tree maximum path sum
`MeetingRooms.kt`	→ meeting rooms
`MeetingRooms_II.kt`	→ meeting rooms
`MeetingRooms_II_greedy.kt`	→ meeting rooms
`MinimumDeletionsToMakeStringBalanced.kt`	→ minimum deletions to make string balanced
`MinimumNumberOfRefuelingStops.kt`	→ minimum number of refueling stops
`MinimumReplacementToSortTheArray.kt`	→ find minimum in rotated sorted array
`MinimumTimeToMakeRopeColorful.kt`	→ minimum time to make rope colorful
`RescheduleMeetingsforMaximumFreeTime_I.kt`	→ reschedule meetings for maximum free time
`TaskScheduler.kt`	→ task scheduler

`grid/` (22 files)

File	Coverage
`FloodFill.kt`	→ flood fill
`IslandPerimeter.kt`	→ island perimeter
`MakingALargeIsland.kt`	→ making a large island
`MakingALargeIsland_AnotherApproach.kt`	→ making a large island
`MaxAreaOfIsland.kt`	variant of max consecutive ones iii
`MaximumNumberOfFishInAGrid.kt`	variant of binary tree maximum path sum
`PacificAtlanticWaterFlow.kt`	variant of container with most water
`RottingOranges.kt`	→ rotting oranges
`ShortestBridge.kt`	support / non-problem
`ShortestDistanceFromAllBuildings.kt`	support / non-problem
`SurroundedRegion.kt`	→ surrounded regions
`SurroundedRegionDfs.kt`	variant of pattern primer: dfs with an undo button
`TrappingRainwater_II.kt`	→ trapping rain water
`WallsAndGates.kt`	→ walls and gates
`ShortestPathInGridWithObstaclesElimination.kt`	support / non-problem
`CherryPickup.kt`	→ cherry pickup
`CherryPickup_II.kt`	→ cherry pickup
`Test.kt`	support / non-problem
`UniquePaths_I.kt`	→ first unique character
`UniquePaths_II.kt`	→ first unique character
`MaximalRectangle.kt`	→ largest rectangle in histogram
`WordSearch_II.kt`	→ design add and search words

`hashtable/` (12 files)

File	Coverage
`CountNumberOfBadPairs.kt`	variant of count rectangles formed by points
`DesignANumberContainerSystem.kt`	→ design auto complete system
`DesignFileSystem.kt`	→ design auto complete system
`DesignHashMap.kt`	variant of design a stack with increment operations
`FirstUniqueCharacter.kt`	→ first unique character
`HIndex.kt`	→ h-index
`IntegerToRoman.kt`	→ roman to integer
`IntersectionOfTwoArray.kt`	→ pattern primer: two pointers & the sorted-array dance
`MaximumFrequencyStack.kt`	variant of binary tree maximum path sum
`RomanToInteger.kt`	→ roman to integer
`WorkBreak_II.kt`	→ word break
`WorlBreak_I_DP.kt`	→ word break

`heap/` (12 files)

File	Coverage
`DualBalancedHeap.kt`	variant of find median from data stream (dual-heap structure)
`FindKClosestElements.kt`	→ find k closest elements
`FindScoreOfAnArrayAfterMarkingAllElements.kt`	variant of find k closest elements
`FindingMKAverage.kt`	→ finding mk average
`IPO.kt`	→ ipo (maximize capital)
`LongestHappyString.kt`	variant of decode string
`MedianFromRunningStream.kt`	→ find median from data stream
`MeetingRoom_III.kt`	→ meeting rooms iii
`SingleThreadedCPU.kt`	→ single threaded cpu
`SlidingWindowMedian.kt`	→ sliding window median
`TopKFrequentElements.kt`	→ top k frequent elements
`TrappingRainWater_II.kt`	→ trapping rain water

`linkedlist/` (23 files)

File	Coverage
`AddTwoNumbers.kt`	→ add two numbers
`CopyLinkedListWithRandomPointer.kt`	variant of linked list cycle
`DeleteMiddleNodeOfLinkedList.kt`	variant of linked list cycle
`InsertIntoASortedCircularLinkedList.kt`	variant of linked list cycle
`InsertIntoASortedCircularList.kt`	variant of flatten nested list iterator
`IntersectionOfTwoLinkedList.kt`	→ linked list cycle
`LinkedListCycle.kt`	→ linked list cycle
`LinkedListCycle_II.kt`	→ linked list cycle
`MaximumTwinSumOfALinkedList.kt`	variant of binary tree maximum path sum
`MergeKSortedList.kt`	→ merge k sorted lists (divide & conquer, top-down)
`MergeKSortedListHeap.kt`	→ merge k sorted lists (heap merge)
`MergeKSortedListIterative.kt`	→ merge k sorted lists (divide & conquer, bottom-up)
`MergeTwoSortedLIst.kt`	→ merge two sorted lists
`MiddleNode.kt`	→ remove nth node from end
`OddEvenLinkedList.kt`	→ linked list cycle
`OddOrEvenLinkedList.kt`	→ linked list cycle
`PalindromeLinkedList.kt`	→ linked list cycle
`RemoveNthNodeFromEndOfList.kt`	→ remove nth node from end
`ReverseLinkedList.kt`	→ reverse linked list
`ReverseLinkedListIterative.kt`	→ reverse linked list
`ReverseNodesInKGroups.kt`	variant of evaluate reverse polish notation
`RotateList.kt`	→ flatten nested list iterator
`SwapNodesInPairs.kt`	variant of shortest path visiting all nodes

`math/` (36 files)

File	Coverage
`AddStrings.kt`	→ add two numbers
`DesignTicTacToe.kt`	variant of design a stack with increment operations
`DetectSquares.kt`	→ word squares
`DivideTwoIntegers.kt`	variant of add two numbers
`HappyNumber.kt`	→ find the duplicate number
`MinimumMovesToEqualArrayElements.kt`	→ find minimum in rotated sorted array
`MultiplyStrings.kt`	→ isomorphic strings
`PlusOne.kt`	→ plus one
`PowerOfTwo.kt`	support / non-problem
`ReverseInteger.kt`	→ evaluate reverse polish notation
`SlidingPuzzle.kt`	→ sliding window maximum
`Sqrt.kt`	variant of sqrt(x)
`StringtoIntegerAtoi.kt`	variant of roman to integer
`AddBinary.kt`	→ add two numbers
`PascalsTriangle.kt`	→ pascal’s triangle
`CheckIfTwoLinesIntrsects.kt`	variant of add two numbers
`ConvexHull.kt`	→ convex hull (erect the fence)
`CountNumberOfTrapizoids_I.kt`	variant of count rectangles formed by points
`ErectTheFence_ConvexHull.kt`	→ convex hull (erect the fence)
`HowManyRectanglesOverlapSweepLine.kt`	→ how many rectangles overlap
`HowManyRectanglesOverlaping.kt`	variant of count rectangles formed by points
`MaxPointsOnALine.kt`	variant of count rectangles formed by points
`RectangleArea.kt`	→ largest rectangle in histogram
`RectangleArea_II.kt`	→ largest rectangle in histogram
`RectangleArea_II_SegmentTree.kt`	variant of binary tree inorder traversal (iterative)
`RectangleOverlap.kt`	→ largest rectangle in histogram
`SeperateSquares_I.kt`	→ word squares
`FindingNumberOfVisibleMountains.kt`	variant of find the duplicate number
`HowManyRectangleOverlapsIntervalTree.kt`	→ how many rectangles overlap
`RectangeOverlapCountTreeSet.kt`	→ how many rectangles overlap
`pow.kt`	support / non-problem
`BasicCalculator.kt`	→ basic calculator ii
`BasicCalculator_I.kt`	→ basic calculator ii
`BasicCalculator_II.kt`	→ basic calculator ii
`BasicCalculator_III.kt`	variant of max consecutive ones iii
`BasicCalculator_II_ShortCode.kt`	→ basic calculator ii

`microsoft/` (3 files)

File	Coverage
`Demo.kt`	support / non-problem
`Toast.kt`	support / non-problem
`ValidTime.kt`	support / non-problem

`ml/` (1 files)

File	Coverage
`DecisionTree.kt`	support / non-problem

`numbers/` (1 files)

File	Coverage
`PalindromeNumber.kt`	→ find the duplicate number

`probability/` (5 files)

File	Coverage
`InsertDeleteGetRandom.kt`	→ insert delete getrandom o(1)
`InsertDeleteGetRandomAtO1.kt`	→ insert delete getrandom o(1)
`LinkedListRandomNode.kt`	→ linked list cycle
`PathWithMaximumProbability.kt`	→ binary tree maximum path sum
`ReservoirSampling.kt`	→ weighted reservoir sampling

`queueu/` (4 files)

File	Coverage
`DesignACircularQueue.kt`	variant of design a stack with increment operations
`DesignHitCounter.kt`	variant of design a stack with increment operations
`NumberOfRecentCalls.kt`	variant of find the duplicate number
`ProductOfLastKNumbers.kt`	variant of find first and last position of target

`quicksort/` (6 files)

File	Coverage
`DualPivotQuickSelect.kt`	→ top k frequent elements (quickselect)
`GenericRanrmoizedQuickSelect.kt`	→ top k frequent elements (quickselect)
`KClosestPointsToOrigin.kt`	→ k closest points to origin
`KThLargestElementInArray.kt`	→ kth largest element
`KthLargestElementInArrayTailRec.kt`	→ kth largest element
`TopKFrequentElements.kt`	→ top k frequent elements

`real_word_projects/` (18 files)

File	Coverage
`HttpApiCall.kt`	support / non-problem
`InterfaceExample.kt`	support / non-problem
`ParallelFibonacci.kt`	support / non-problem
`ScaleTransactions.kt`	support / non-problem
`SystemInterviewHack.kt`	support / non-problem
`TradingAPICallExample.kt`	support / non-problem
`DataModels.kt`	support / non-problem
`ChannelsExample.kt`	support / non-problem
`SimpleThreadPool.kt`	support / non-problem
`ConsistentHashing.kt`	support / non-problem
`AiTest.kt`	support / non-problem
`DuckworthLewisStern.kt`	support / non-problem
`JsonExample.kt`	support / non-problem
`CheckIfIPBelongsToNetworkAddress.kt`	variant of critical connections in a network
`FindMaxInArray.kt`	→ find minimum in rotated sorted array
`ParallelMatrixMultiplication.kt`	support / non-problem
`AlpacaSDKExamples.kt`	support / non-problem
`RealtimeMarketDataStreaming.kt`	variant of find median from data stream

`simulation/` (7 files)

File	Coverage
`CarPooling.kt`	→ car fleet
`CountCollisionsOnARoad.kt`	variant of count rectangles formed by points
`FindWinnerOnATicTacToeGame.kt`	→ find winner on a tictactoe game
`LatestTimeToCatchBus.kt`	support / non-problem
`Racecar.kt`	→ racecar
`RobotBoundedInCircle.kt`	→ robot bounded in circle
`TextJustification.kt`	→ text justification

`sliding_window/` (14 files)

File	Coverage
`LongestContinuousSubarrayWithAbsoluteDifferenceLessThanOrEqualToLimit.kt`	variant of longest common prefix
`LongestRepeatingCharacterReplacement.kt`	→ longest repeating character replacement
`LongestSubArraysOfOneAfterDeletingOneElement.kt`	→ longest subarray of 1s after deleting one
`LongestSubstringWithoutRepeatingCharacter.kt`	→ longest repeating character replacement
`MaxConsecutiveOnes_III.kt`	→ max consecutive ones iii
`MaximumAverageSubarray_I.kt`	→ maximum average subarray i
`MaximumErasureValue.kt`	variant of binary tree maximum path sum
`MaximumSumOfDistinctSubarraysWithLengthK.kt`	variant of binary tree maximum path sum
`MinimumSizeSubarraySum.kt`	→ minimum size subarray sum
`MinimumSwapsToGroupAllOnesTogether.kt`	→ minimum operations to move all balls
`MinimumWindowSubstring.kt`	→ minimum window substring
`PartitionLabels.kt`	→ partition equal subset sum
`ProgrammerString.kt`	→ decode string
`SlidingWindowMaximum.kt`	→ sliding window maximum

`sorting/` (6 files)

File	Coverage
`EmployeeFreeTime.kt`	variant of best time to buy and sell stock ii
`HIndex.kt`	→ h-index
`LargestNumber.kt`	→ largest number
`MergeSort.kt`	→ merge sort
`RankTeamsByVote.kt`	→ rank teams by votes
`RussianDollEnvelope.kt`	→ russian doll envelopes

`speed_dating/` (1 files)

File	Coverage
`ComputerScienceEngineerDating.kt`	support / non-problem

`stack/` (27 files)

File	Coverage
`AestroidCollisions.kt`	→ asteroid collision
`BuildingsWithAnOceanView.kt`	variant of binary tree right side view
`DailyTemperatures.kt`	→ daily temperatures
`DesignAStackWithIncrementOperations.kt`	→ design a stack with increment operations
`EvaluateReversePolishNotation.kt`	→ evaluate reverse polish notation
`ExclusiveTimeOfFunctions.kt`	variant of best time to buy and sell stock ii
`FlattenNestedListIterator.kt`	→ flatten nested list iterator
`LargestRectangleInHistogram.kt`	→ largest rectangle in histogram
`LongestValidParanthesis.kt`	→ longest valid parentheses
`MinStack.kt`	→ min stack
`MinStackShort.kt`	→ min stack
`MinimumAddtoMakeParenthesesValid.kt`	variant of longest valid parentheses
`MinimumDeletionsToMakeStringBalanced.kt`	→ minimum deletions to make string balanced
`MinimumOperationstoConvertAllElementstoZero.kt`	→ minimum operations to convert all elements to zero
`MinimumRemoveToMakeValidParentheses.kt`	variant of longest valid parentheses
`NextGreaterElement_I.kt`	→ next greater element ii
`NextGreaterElement_II.kt`	→ next greater element ii
`NumberOfVisiblePeopleInAQueue.kt`	variant of find the duplicate number
`OneThreeTwoPattern.kt`	→ pattern primer: o(1) lookup, three moves
`OnlineStockSpan.kt`	variant of best time to buy and sell stock ii
`RemoveDuplicateLetters.kt`	variant of contains duplicate ii
`RemoveKDigits.kt`	→ remove k digits
`RemoveStarsFromString.kt`	variant of decode string
`SmallestSubsequenceOfDistinctCharacters.kt`	variant of closest subsequence sum
`SumOfSubArrayMinimum.kt`	→ find minimum in rotated sorted array
`SumOfSubArrayRanges.kt`	variant of binary tree maximum path sum
`ValidParentheses.kt`	→ longest valid parentheses

`stock_market/` (5 files)

File	Coverage
`BestTimeToBuyAndSellStock.kt`	→ best time to buy and sell stock ii
`BestTimeToBuyAndSellStockWithCooldown.kt`	→ best time to buy and sell stock ii
`BestTimeToBuyAndSellStockWithTransactionFee.kt`	→ best time to buy and sell stock ii
`BestTimeToBuyAndSellStock_III.kt`	→ best time to buy and sell stock ii
`BestTimeToBuyAndSellStock_II.kt`	→ best time to buy and sell stock ii

`stream/` (1 files)

File	Coverage
`MovingAverageOfARunningStream.kt`	variant of find median from data stream

`string/` (69 files)

File	Coverage
`ApplySubstitutions.kt`	→ apply substitutions
`CheckifaParenthesesStringCanBeValid.kt`	variant of longest valid parentheses
`CountAndSay.kt`	→ count rectangles formed by points
`CountNumberOfWordsWhichAreSubSequence.kt`	variant of count words with a given prefix
`CountWordsWithAGivenPrefix.kt`	→ count words with a given prefix
`DetectCapital.kt`	→ ipo (maximize capital)
`ExcelSheetToColumnNumber.kt`	variant of find the duplicate number
`FindUniqueBinaryString.kt`	variant of binary tree inorder traversal (iterative)
`GoatLatin.kt`	→ goat latin
`GreatestCommonDivisorOfStrings.kt`	support / non-problem
`GroupAnagrams.kt`	→ group anagrams
`IsSubsequence.kt`	→ closest subsequence sum
`IsomorphicString.kt`	→ decode string
`LengthOfLastWord.kt`	variant of find first and last position of target
`LongestCommonPrefix.kt`	→ longest common prefix
`LongestPalidnromicSubstring.kt`	→ longest common substring
`MaximumLengthofaConcatenatedStringwithUniqueCharacters.kt`	→ maximum length of concatenated string
`MaximumNumberOfNonOverlappingPalindromicSubstring.kt`	variant of longest palindromic substring
`MaximumValueAfterInsertion.kt`	variant of binary tree maximum path sum
`MaximumValueOfAStringIsAnArray.kt`	variant of binary tree maximum path sum
`MergeStringAlternatively.kt`	variant of decode string
`MinimumDeletionToMakeCharacterFrequenciesUnique.kt`	variant of first unique character
`ReverseVowelOfString.kt`	→ reverse words in a string
`ReverseWordsInString.kt`	→ reverse words in a string
`StringCompression.kt`	→ decode string
`StringCompression_II.kt`	→ decode string
`ValidAnagram.kt`	→ valid anagram
`ValidNumber.kt`	→ find the duplicate number
`ValidPalindrome.kt`	→ valid palindrome
`ValidPalindrome_II.kt`	→ valid palindrome
`ValidWordAbbreviation.kt`	variant of longest valid parentheses
`ValidateIPAddress.kt`	→ validate ip address
`ValidateIPAddressBetterImplementation.kt`	variant of validate ip address
`GenerateParantheses.kt`	→ generate parentheses
`WordBreak_II.kt`	→ word break
`WordSquare.kt`	→ maximal square
`DeleteOperationsForTwoStrings.kt`	variant of add two numbers
`EditDistance.kt`	→ minimum edit distance
`InterleavingString.kt`	→ decode string
`LongestCommonSubsequence.kt`	→ longest common subsequence
`LongestCommonSubstring.kt`	→ longest common substring
`LongestPalindromicSubsequence.kt`	→ longest common subsequence
`LongestPalindromicSubsequence_BottomUp.kt`	→ longest common subsequence
`LongestStringChain.kt`	variant of decode string
`PalindromePartitioning_II.kt`	→ palindrome partitioning
`RegularExpressionMatching.kt`	variant of maximum bipartite matching
`ShortestCommonSuperSequence_Modular.kt`	support / non-problem
`ShortestCommonSupersequence.kt`	support / non-problem
`ValidPalindrome_III.kt`	→ valid palindrome
`ValidPalindrome_III_SpaceOptimized.kt`	variant of valid palindrome
`BreakAPalindrome.kt`	→ word break
`ShortestWayToFormAString.kt`	support / non-problem
`DetermineIfStringsAreClose.kt`	variant of isomorphic strings
`GroupShiftedStrings.kt`	variant of group anagrams
`PermutationsInString.kt`	→ decode string
`UniqueLength3PalindromicSubsequence.kt`	variant of closest subsequence sum
`UniqueSubstringWithEqualDigitFrequency.kt`	variant of first unique character
`BengaliProgramming.kt`	support / non-problem
`FindTheIndexofTheFirstOccurrenceIna String.kt`	→ find the index of the first occurrence (kmp)
`FindTheIndexofTheFirstOccurrenceIna String_RabinKarp.kt`	→ find the index of the first occurrence (rabin-karp)
`FindAllAnagrams.kt`	variant of find first and last position of target
`MaximumNumberofVowelsinSubstringofGivenLength.kt`	→ maximum length of concatenated string
`MinimumWindowSubsequence.kt`	→ minimum window substring
`MinimumWindowSubstring.kt`	→ minimum window substring
`CustomSortString.kt`	variant of decode string
`CustomSortString_Linear.kt`	variant of decode string
`DecodeString.kt`	→ decode string
`RemoveAllAdjacentDuplicatesInString.kt`	→ remove all adjacent duplicates
`SimplifyPath.kt`	→ binary tree maximum path sum

`tree/` (71 files)

File	Coverage
`AllNodesDistanceKinBinaryTree.kt`	variant of binary tree inorder traversal (iterative)
`BInaryTreeInOrderTraversalIterative.kt`	→ binary tree inorder traversal (iterative)
`BalancedBinaryTree.kt`	→ binary tree inorder traversal (iterative)
`BinaryTreeLevelOrderTraversal.kt`	→ binary tree level order traversal
`BinaryTreeMaximumPathSum.kt`	→ binary tree maximum path sum
`BinaryTreeRightSideView.kt`	→ binary tree right side view
`BinaryTreeVerticalOrderTraversal.kt`	→ binary tree level order traversal
`BinaryTreeVerticalOrderTraversal_WithoutSorting.kt`	→ binary tree level order traversal
`BinaryTreeZigZagLevelOrderTraversal.kt`	→ binary tree level order traversal
`BoundaryOfBinaryTree.kt`	→ binary tree inorder traversal (iterative)
`ConstructBinaryTreeFromInorderAndPostOrderTraversal.kt`	→ binary tree inorder traversal (iterative)
`ConstructBinaryTreeFromPreorderAndInOrderTraversal.kt`	→ binary tree level order traversal
`ConstructBinaryTreeFromString.kt`	→ binary tree inorder traversal (iterative)
`CountGoodNodeInBInaryTree.kt`	variant of binary tree inorder traversal (iterative)
`CountNodeEqualsAverage.kt`	variant of count rectangles formed by points
`DiameterOfNArrayTree.kt`	→ diameter of binary tree
`LeafSimilar.kt`	→ leaf-similar trees
`LongestPathWithDifferentAdjacentCharacters.kt`	variant of longest substring without repeating characters
`LongestUnivaluePath.kt`	variant of binary tree maximum path sum
`LowestCommonAncestor.kt`	→ lowest common ancestor
`LowestCommonAncestor_III.kt`	→ lowest common ancestor
`MaximumDepthOfBinaryTree.kt`	→ maximum depth of binary tree
`MaximumLevelSumOfABinaryTreee.kt`	variant of binary tree maximum path sum
`MaximumProductOfSplittedBinaryTree.kt`	→ binary tree maximum path sum
`MaximumSumBSTInBinaryTree.kt`	→ binary tree maximum path sum
`MaximumWidthOfBinaryTree.kt`	→ binary tree maximum path sum
`MinimumTimeToCollectAllApplesInATree.kt`	→ minimum time to collect all apples
`PathSum.kt`	→ binary tree maximum path sum
`PathSumIII.kt`	→ path sum iii
`PathSum_II.kt`	→ binary tree maximum path sum
`PopulateNextRightPointersInEachNode_II.kt`	→ populating next right pointers in each node
`PopulateNextRightPointersInEachNode_II_Constant.kt`	→ populating next right pointers in each node
`PopulatingNextRightPointerInEachNode.kt`	→ populating next right pointers in each node
`RecoverATreeFromPreOrderTraversal.kt`	variant of binary tree level order traversal
`SerializeAndDeserializeABinaryTree.kt`	→ serialize and deserialize binary tree
`SerializeAndDeserializeNArrayTree.kt`	→ serialize and deserialize binary tree
`SlidingWindowMedianTreeSet.kt`	→ sliding window median
`StepByStepDirectionsFromANodeToAnother.kt`	→ step-by-step directions
`SumRootToLeafNumbers.kt`	variant of add two numbers
`VerticalOrderTraversalOfABinaryTree.kt`	→ binary tree level order traversal
`AverageOfLevelsInBinaryTree.kt`	→ binary tree inorder traversal (iterative)
`BinaryTreeLevelOrderTraversal_II.kt`	→ binary tree level order traversal
`CheckCompletenessOfBinaryTree.kt`	→ binary tree inorder traversal (iterative)
`FindLargestValueInEachTreeRow.kt`	→ find largest value in each tree row
`BSTIterator.kt`	→ bst iterator
`ClosestBinarySearchTreeValue.kt`	variant of binary tree inorder traversal (iterative)
`ConvertBInarySearchTreeToSortedDoublyLinkedList.kt`	variant of binary tree inorder traversal (iterative)
`DeleteNodeinABST.kt`	variant of insert delete getrandom o(1)
`GetClosestElement.kt`	variant of closest subsequence sum
`InorderSuccessor.kt`	→ binary tree inorder traversal (iterative)
`LongestIncreasingSubsequence.kt`	→ longest increasing subsequence
`MinimumNumberOfRemovalsToMakeMountainArray.kt`	variant of find minimum in rotated sorted array
`MyCalendar.kt`	→ my calendar
`OrderedStatisticsTree.kt`	variant of binary tree inorder traversal (iterative)
`OrderedStatisticsTreeForStreamers.kt`	variant of binary tree inorder traversal (iterative)
`RecoverBinarySearchTree.kt`	→ binary tree inorder traversal (iterative)
`SkylineProblem.kt`	→ the skyline problem
`StreamerRanking.kt`	→ streamer leaderboard
`UniqueBinarySearchTrees.kt`	→ pattern primer: the binary search theorem
`UniqueBinarySearchTrees_II.kt`	→ pattern primer: the binary search theorem
`CountOfSmallerNumberAfterSelf.kt`	variant of count rectangles formed by points
`FenwickTree.kt`	support / non-problem
`RangeSumQuery2dMutable.kt`	variant of binary tree maximum path sum
`RangeSumQueryMutable.kt`	variant of binary tree maximum path sum
`IntervalTree.kt`	→ binary tree inorder traversal (iterative)
`MinCostToConnectAllPointsKruskal.kt`	→ min cost to connect all points
`MinCostToConnectAllPointsPrims.kt`	→ min cost to connect all points (prim’s)
`DynamicSegmentTree.kt`	variant of binary tree inorder traversal (iterative)
`IterativeSegmentTree.kt`	→ binary tree inorder traversal (iterative)
`MyCalendar_II.kt`	→ my calendar ii
`SegmentTree.kt`	→ binary tree inorder traversal (iterative)

`trie/` (12 files)

File	Coverage
`AbstractTrie.kt`	→ implement trie (prefix tree)
`AutoCompleteSystem.kt`	→ design auto complete system
`AutoCompleteSystemWithHeap.kt`	→ design auto complete system
`CountWordsWithAGivenPrefix_Trie.kt`	→ count words with a given prefix
`CountWordsWithAGivenPrefix_Trie_FP.kt`	→ count words with a given prefix
`DesignAddAndSearchWordDataStructure.kt`	→ design add and search words
`EqualRowAndColumnPairs.kt`	→ equal row and column pairs
`LongestCommonPrefix.kt`	→ longest common prefix
`SearchSuggestionSystem.kt`	→ search suggestion system
`WordBreak_I.kt`	→ word break
`WordSquare.kt`	→ maximal square
`WordSquaresShorter.kt`	→ word squares

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