Arrays & Hashing
9 problemsTwo SumContains DuplicateValid AnagramGroup AnagramsTop K Frequent ElementsProduct of Array Except SelfValid SudokuEncode and Decode Strings+1 more
Two Pointers
5 problemsValid Palindrome3SumContainer With Most WaterTwo Sum IITrapping Rain Water
Sliding Window
6 problemsBest Time to Buy and Sell StockLongest Substring Without RepeatingLongest Repeating Character ReplacementPermutation in StringMinimum Window SubstringSliding Window Maximum
Stack
7 problemsValid ParenthesesMin StackEvaluate Reverse Polish NotationGenerate ParenthesesDaily TemperaturesCar FleetLargest Rectangle in Histogram
Binary Search
7 problemsBinary SearchSearch a 2D MatrixKoko Eating BananasFind Minimum in Rotated Sorted ArraySearch in Rotated Sorted ArrayTime Based Key-Value StoreMedian of Two Sorted Arrays
Linked List
6 problemsReverse Linked ListMerge Two Sorted ListsLinked List CycleReorder ListRemove Nth Node From End of ListMerge k Sorted Lists
Trees
11 problemsInvert Binary TreeMaximum Depth of Binary TreeSame TreeSubtree of Another TreeLowest Common Ancestor of BSTBinary Tree Level Order TraversalValidate BSTKth Smallest Element in BST+3 more
Tries
3 problemsImplement Trie (Prefix Tree)Design Add and Search WordsWord Search II
Heap / Priority Queue
3 problemsKth Largest Element in a StreamLast Stone WeightK Closest Points to OriginKth Largest Element in an ArrayTask SchedulerDesign TwitterFind Median from Data Stream
Backtracking
5 problemsSubsetsCombination SumPermutationsSubsets IICombination Sum IIWord SearchPalindrome PartitioningLetter Combinations of a Phone Number+1 more
Graphs
6 problemsNumber of IslandsClone GraphPacific Atlantic Water FlowCourse ScheduleNumber of Connected Components in Undirected GraphGraph Valid Tree
Dynamic Programming
7 problemsClimbing StairsHouse RobberHouse Robber IILongest Palindromic SubstringPalindromic SubstringsDecode WaysCoin ChangeMaximum Product Subarray+3 more