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The revision library.

Complete Blind 75 and NeetCode 150 collections. Open a card for the insight, correctness argument and commented Java solution.

75 problems

#ProblemTopicLevelRecall☆

01Two SumArrays & hashingEasyNot reviewed

02Valid AnagramArrays & hashingEasyNot reviewed

03Contains DuplicateArrays & hashingEasyNot reviewed

04Group AnagramsArrays & hashingMediumNot reviewed

05Product of Array Except SelfArrays & hashingMediumNot reviewed

06Valid PalindromeTwo pointersEasyNot reviewed

073SumTwo pointersMediumNot reviewed

08Container With Most WaterTwo pointersMediumNot reviewed

09Best Time to Buy and Sell StockSliding windowEasyNot reviewed

10Longest Substring Without Repeating CharactersSliding windowMediumNot reviewed

11Longest Repeating Character ReplacementSliding windowMediumNot reviewed

12Minimum Window SubstringSliding windowHardNot reviewed

13Valid ParenthesesStackEasyNot reviewed

14Find Minimum in Rotated Sorted ArrayBinary searchMediumNot reviewed

15Search in Rotated Sorted ArrayBinary searchMediumNot reviewed

16Invert Binary TreeTreesEasyNot reviewed

17Maximum Depth of Binary TreeTreesEasyNot reviewed

18Same TreeTreesEasyNot reviewed

19Maximum SubarrayDynamic programmingMediumNot reviewed

20Maximum Product SubarrayDynamic programmingMediumNot reviewed

21Sum of Two IntegersBit manipulationMediumNot reviewed

22Number of 1 BitsBit manipulationEasyNot reviewed

23Counting BitsBit manipulationEasyNot reviewed

24Missing NumberBit manipulationEasyNot reviewed

25Reverse BitsBit manipulationEasyNot reviewed

26Climbing StairsDynamic programmingEasyNot reviewed

27Coin ChangeDynamic programmingMediumNot reviewed

28Longest Increasing SubsequenceDynamic programmingMediumNot reviewed

29Longest Common SubsequenceDynamic programmingMediumNot reviewed

30Word BreakDynamic programmingMediumNot reviewed

31Combination Sum IVDynamic programmingMediumNot reviewed

32House RobberDynamic programmingMediumNot reviewed

33House Robber IIDynamic programmingMediumNot reviewed

34Decode WaysDynamic programmingMediumNot reviewed

35Unique PathsDynamic programmingMediumNot reviewed

36Jump GameGreedyMediumNot reviewed

37Clone GraphGraphsMediumNot reviewed

38Course ScheduleGraphsMediumNot reviewed

39Pacific Atlantic Water FlowGraphsMediumNot reviewed

40Number of IslandsGraphsMediumNot reviewed

41Longest Consecutive SequenceArrays & hashingMediumNot reviewed

42Alien DictionaryGraphsHardNot reviewed

43Graph Valid TreeGraphsMediumNot reviewed

44Connected Components in an Undirected GraphGraphsMediumNot reviewed

45Insert IntervalIntervalsMediumNot reviewed

46Merge IntervalsIntervalsMediumNot reviewed

47Non-overlapping IntervalsIntervalsMediumNot reviewed

48Meeting RoomsIntervalsEasyNot reviewed

49Meeting Rooms IIIntervalsMediumNot reviewed

50Reverse Linked ListLinked listsEasyNot reviewed

51Linked List CycleLinked listsEasyNot reviewed

52Merge Two Sorted ListsLinked listsEasyNot reviewed

53Merge K Sorted ListsHeapsHardNot reviewed

54Remove Nth Node From End of ListLinked listsMediumNot reviewed

55Reorder ListLinked listsMediumNot reviewed

56Set Matrix ZeroesMatricesMediumNot reviewed

57Spiral MatrixMatricesMediumNot reviewed

58Rotate ImageMatricesMediumNot reviewed

59Word SearchBacktrackingMediumNot reviewed

60Longest Palindromic SubstringStringsMediumNot reviewed

61Palindromic SubstringsStringsMediumNot reviewed

62Encode and Decode StringsStringsMediumNot reviewed

63Binary Tree Maximum Path SumTreesHardNot reviewed

64Binary Tree Level Order TraversalTreesMediumNot reviewed

65Serialize and Deserialize Binary TreeTreesHardNot reviewed

66Subtree of Another TreeTreesEasyNot reviewed

67Build Tree from Preorder and InorderTreesMediumNot reviewed

68Validate Binary Search TreeTreesMediumNot reviewed

69Kth Smallest Element in a BSTTreesMediumNot reviewed

70Lowest Common Ancestor of a BSTTreesMediumNot reviewed

71Implement TrieTriesMediumNot reviewed

72Design Add and Search WordsTriesMediumNot reviewed

73Word Search IITriesHardNot reviewed

74Top K Frequent ElementsHeapsMediumNot reviewed

75Find Median from Data StreamHeapsHardNot reviewed

All 75 original Blind 75 questions and all 150 NeetCode 150 questions are included. Questions shared by both collections use the same notes and progress. Some source problems require LeetCode Premium; all original revision notes here are free. Guest progress stays in this browser. Use Account & sync for cloud availability, or export a backup to move devices.