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Classic coding-interview problems. Write your solution in JavaScript or Java, run the examples, submit against hidden tests and compare with the optimal approach. Your code and progress are saved in this browser.
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StatusTitleTopicsSolved inDifficulty
Two SumArrayHash TableEasyValid ParenthesesStringStackEasyReverse Linked ListLinked ListRecursionEasyMaximum Depth of Binary TreeTreeBinary TreeDFSEasyMove ZeroesArrayTwo PointersEasyGroup AnagramsArrayHash TableStringMediumMin StackStackDesignMediumContains DuplicateArrayHash TableSortingEasyValid AnagramStringHash TableSortingEasyBest Time to Buy and Sell StockArrayGreedyDynamic ProgrammingEasyMajority ElementArrayHash TableSortingEasyValid PalindromeStringTwo PointersEasyTop K Frequent ElementsArrayHash TableHeapMediumProduct of Array Except SelfArrayPrefix SumMediumLongest Consecutive SequenceArrayHash TableMedium3SumArrayTwo PointersSortingMediumContainer With Most WaterArrayTwo PointersGreedyMediumLongest Substring Without Repeating CharactersStringHash TableSliding WindowMediumLongest Repeating Character ReplacementStringHash TableSliding WindowMediumSubarray Sum Equals KArrayHash TablePrefix SumMediumTrapping Rain WaterArrayTwo PointersDynamic ProgrammingHardMinimum Window SubstringStringHash TableSliding WindowHardBinary SearchArrayBinary SearchEasyMerge Two Sorted ListsLinked ListRecursionEasyEvaluate Reverse Polish NotationArrayStackMathMediumDaily TemperaturesArrayStackMediumGenerate ParenthesesStringBacktrackingRecursionMediumSearch in Rotated Sorted ArrayArrayBinary SearchMediumFind Minimum in Rotated Sorted ArrayArrayBinary SearchMediumKoko Eating BananasArrayBinary SearchMediumRemove Nth Node From End of ListLinked ListTwo PointersMediumAdd Two NumbersLinked ListMathRecursionMediumReorder ListLinked ListTwo PointersRecursionMediumLRU CacheHash TableLinked ListDesignMediumLargest Rectangle in HistogramArrayStackHardMerge k Sorted ListsLinked ListHeapSortingHardMedian of Two Sorted ArraysArrayBinary SearchHardInvert Binary TreeTreeBinary TreeDFSEasySame TreeTreeBinary TreeDFSEasyDiameter of Binary TreeTreeBinary TreeDFSEasyBinary Tree Level Order TraversalTreeBinary TreeBFSMediumValidate Binary Search TreeTreeBSTDFSMediumKth Smallest Element in a BSTTreeBSTDFSMediumLowest Common Ancestor of a BSTTreeBSTBinary SearchMediumBinary Tree Right Side ViewTreeBinary TreeBFSMediumConstruct Binary Tree from Preorder and Inorder TraversalTreeBinary TreeHash TableMediumImplement Trie (Prefix Tree)TrieDesignStringMediumKth Largest Element in an ArrayArrayHeapSortingMediumK Closest Points to OriginArrayHeapMathMediumTask SchedulerArrayHash TableGreedyMediumFind Median from Data StreamHeapDesignSortingHardBinary Tree Maximum Path SumTreeBinary TreeDFSHardClimbing StairsDynamic ProgrammingMathRecursionEasyHouse RobberArrayDynamic ProgrammingMediumCoin ChangeArrayDynamic ProgrammingBFSMediumLongest Increasing SubsequenceArrayDynamic ProgrammingBinary SearchMediumUnique PathsDynamic ProgrammingMathMatrixMediumWord BreakStringDynamic ProgrammingHash TableMediumJump GameArrayGreedyDynamic ProgrammingMediumMerge IntervalsArraySortingIntervalsMediumNon-overlapping IntervalsArrayGreedySortingMediumNumber of IslandsGraphDFSBFSMediumRotting OrangesBFSMatrixGraphMediumCourse ScheduleGraphDFSBFSMediumSubsetsArrayBacktrackingBit ManipulationMediumPermutationsArrayBacktrackingRecursionMediumCombination SumArrayBacktrackingMediumWord SearchBacktrackingMatrixDFSMediumLongest Common SubsequenceStringDynamic ProgrammingMediumEdit DistanceStringDynamic ProgrammingHardNo problems match those filters.