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Hash Table

407 questions

1Longest Substring Without Repeating CharactersMedium
Hash TableStringSliding Window
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2Reorganize StringMedium
Hash TableStringGreedy
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3LRU CacheMedium
Hash TableLinked ListDesign
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4Minimum Window SubstringHard
Hash TableStringSliding Window
Solve →
5Word LadderHard
Hash TableStringBreadth-First Search
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6Valid AnagramEasy
Hash TableStringSorting
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7Maximum Number of BalloonsEasy
Hash TableStringCounting
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8Copy List with Random PointerMedium
Hash TableLinked List
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9Isomorphic StringsEasy
Hash TableString
Solve →
10Optimal Partition of StringMedium
Hash TableStringGreedy
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11Intersection of Two Linked ListsEasy
Hash TableLinked ListTwo Pointers
Solve →
12Happy NumberEasy
Hash TableMathTwo Pointers
Solve →
13LRU CacheMedium
Hash TableLinked ListDesign
Solve →
14Longest Substring Without Repeating CharactersMedium
Hash TableStringSliding Window
Solve →
15Reorganize StringMedium
Hash TableStringGreedy
Solve →
16Copy List with Random PointerMedium
Hash TableLinked List
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17Longest Repeating Character ReplacementMedium
Hash TableStringSliding Window
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18Minimum Window SubstringHard
Hash TableStringSliding Window
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19Time Based Key-Value StoreMedium
Hash TableStringBinary Search
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20Valid AnagramEasy
Hash TableStringSorting
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21Letter Combinations of a Phone NumberMedium
Hash TableStringBacktracking
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22Linked List Cycle IIMedium
Hash TableLinked ListTwo Pointers
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23Isomorphic StringsEasy
Hash TableString
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24Word LadderHard
Hash TableStringBreadth-First Search
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25First Unique Character in a StringEasy
Hash TableStringQueue
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26Integer to RomanMedium
Hash TableMathString
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27Ransom NoteEasy
Hash TableStringCounting
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28Roman to IntegerEasy
Hash TableMathString
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29Linked List CycleEasy
Hash TableLinked ListTwo Pointers
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30All Nodes Distance K in Binary TreeMedium
Hash TableTreeDepth-First Search
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31Largest Palindromic NumberMedium
Hash TableStringGreedy
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32Permutation in StringMedium
Hash TableTwo PointersString
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33Vertical Order Traversal of a Binary TreeHard
Hash TableTreeDepth-First Search
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34Amount of Time for Binary Tree to Be InfectedMedium
Hash TableTreeDepth-First Search
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35LFU CacheHard
Hash TableLinked ListDesign
Solve →
36Count the Number of Special Characters IEasy
Hash TableString
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37Intersection of Two Linked ListsEasy
Hash TableLinked ListTwo Pointers
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38Happy NumberEasy
Hash TableMathTwo Pointers
Solve →
39Maximum Number of BalloonsEasy
Hash TableStringCounting
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40Clone GraphMedium
Hash TableDepth-First SearchBreadth-First Search
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41Lowest Common Ancestor of a Binary Tree IIIMedium
Hash TableTwo PointersTree
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42Bulls and CowsMedium
Hash TableStringCounting
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43Substring with Concatenation of All WordsHard
Hash TableStringSliding Window
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44Word PatternEasy
Hash TableString
Solve →
45Logger Rate LimiterEasy
Hash TableDesignData Stream
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46Find All Anagrams in a StringMedium
Hash TableStringSliding Window
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47Substring With Largest VarianceHard
Hash TableStringDynamic Programming
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48Partition LabelsMedium
Hash TableTwo PointersString
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49Sort Characters By FrequencyMedium
Hash TableStringSorting
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50Minimum Genetic MutationMedium
Hash TableStringBreadth-First Search
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51Total Appeal of A StringHard
Hash TableStringDynamic Programming
Solve →
52Optimal Partition of StringMedium
Hash TableStringGreedy
Solve →
53Buddy StringsEasy
Hash TableString
Solve →
54Jewels and StonesEasy
Hash TableString
Solve →
55Longest Substring Without Repeating CharactersMedium
Hash TableStringSliding Window
Solve →
56LRU CacheMedium
Hash TableLinked ListDesign
Solve →
57Reorganize StringMedium
Hash TableStringGreedy
Solve →
58Letter Combinations of a Phone NumberMedium
Hash TableStringBacktracking
Solve →
59Longest Repeating Character ReplacementMedium
Hash TableStringSliding Window
Solve →
60Word LadderHard
Hash TableStringBreadth-First Search
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61Valid AnagramEasy
Hash TableStringSorting
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62Copy List with Random PointerMedium
Hash TableLinked List
Solve →
63Minimum Window SubstringHard
Hash TableStringSliding Window
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64First Unique Character in a StringEasy
Hash TableStringQueue
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65Linked List Cycle IIMedium
Hash TableLinked ListTwo Pointers
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66Time Based Key-Value StoreMedium
Hash TableStringBinary Search
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67Happy NumberEasy
Hash TableMathTwo Pointers
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68Intersection of Two Linked ListsEasy
Hash TableLinked ListTwo Pointers
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69Vertical Order Traversal of a Binary TreeHard
Hash TableTreeDepth-First Search
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70Integer to RomanMedium
Hash TableMathString
Solve →
71Isomorphic StringsEasy
Hash TableString
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72Permutation in StringMedium
Hash TableTwo PointersString
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73Roman to IntegerEasy
Hash TableMathString
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74Linked List CycleEasy
Hash TableLinked ListTwo Pointers
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75All Nodes Distance K in Binary TreeMedium
Hash TableTreeDepth-First Search
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76Ransom NoteEasy
Hash TableStringCounting
Solve →
77Amount of Time for Binary Tree to Be InfectedMedium
Hash TableTreeDepth-First Search
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78LFU CacheHard
Hash TableLinked ListDesign
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79Sort Characters By FrequencyMedium
Hash TableStringSorting
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80Most Stones Removed with Same Row or ColumnMedium
Hash TableDepth-First SearchUnion-Find
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81Clone GraphMedium
Hash TableDepth-First SearchBreadth-First Search
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82Lowest Common Ancestor of a Binary Tree IIIMedium
Hash TableTwo PointersTree
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83Longest Substring with At Least K Repeating CharactersMedium
Hash TableStringDivide and Conquer
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84Substring with Concatenation of All WordsHard
Hash TableStringSliding Window
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85Word Ladder IIHard
Hash TableStringBacktracking
Solve →
86Largest Palindromic NumberMedium
Hash TableStringGreedy
Solve →
87Find All Anagrams in a StringMedium
Hash TableStringSliding Window
Solve →
88Logger Rate LimiterEasy
Hash TableDesignData Stream
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89Find the DifferenceEasy
Hash TableStringBit Manipulation
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90Two Sum IV - Input is a BSTEasy
Hash TableTwo PointersTree
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91Longest Balanced Substring IMedium
Hash TableStringCounting
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92Check If a String Contains All Binary Codes of Size KMedium
Hash TableStringBit Manipulation
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93Bulls and CowsMedium
Hash TableStringCounting
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94Repeated DNA SequencesMedium
Hash TableStringBit Manipulation
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95Count the Number of Special Characters IEasy
Hash TableString
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96Buddy StringsEasy
Hash TableString
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97Jewels and StonesEasy
Hash TableString
Solve →
98Maximum Number of BalloonsEasy
Hash TableStringCounting
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99Partition LabelsMedium
Hash TableTwo PointersString
Solve →
100Design File SystemMedium
Hash TableStringDesign
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101Design TwitterMedium
Hash TableLinked ListDesign
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102Number of AtomsHard
Hash TableStringStack
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103Longest Balanced Substring IIMedium
Hash TableStringPrefix Sum
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104Check if Strings Can be Made Equal With Operations IIMedium
Hash TableStringSorting
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105Word PatternEasy
Hash TableString
Solve →
106Design Task ManagerMedium
Hash TableDesignHeap (Priority Queue)
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107Maximum Frequency StackHard
Hash TableStackDesign
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108All O`one Data StructureHard
Hash TableLinked ListDesign
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109Substring With Largest VarianceHard
Hash TableStringDynamic Programming
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110K-Similar StringsHard
Hash TableStringBreadth-First Search
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111Minimum Genetic MutationMedium
Hash TableStringBreadth-First Search
Solve →
112Total Appeal of A StringHard
Hash TableStringDynamic Programming
Solve →
113Optimal Partition of StringMedium
Hash TableStringGreedy
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114Check if the Sentence Is PangramEasy
Hash TableString
Solve →
115LRU CacheMedium
Hash TableLinked ListDesign
Solve →
116Longest Substring Without Repeating CharactersMedium
Hash TableStringSliding Window
Solve →
117Reorganize StringMedium
Hash TableStringGreedy
Solve →
118Copy List with Random PointerMedium
Hash TableLinked List
Solve →
119Word LadderHard
Hash TableStringBreadth-First Search
Solve →
120Roman to IntegerEasy
Hash TableMathString
Solve →
121Letter Combinations of a Phone NumberMedium
Hash TableStringBacktracking
Solve →
122Valid AnagramEasy
Hash TableStringSorting
Solve →
123Minimum Window SubstringHard
Hash TableStringSliding Window
Solve →
124Longest Repeating Character ReplacementMedium
Hash TableStringSliding Window
Solve →
125LFU CacheHard
Hash TableLinked ListDesign
Solve →
126All Nodes Distance K in Binary TreeMedium
Hash TableTreeDepth-First Search
Solve →
127Integer to RomanMedium
Hash TableMathString
Solve →
128First Unique Character in a StringEasy
Hash TableStringQueue
Solve →
129Happy NumberEasy
Hash TableMathTwo Pointers
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130Linked List CycleEasy
Hash TableLinked ListTwo Pointers
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131Isomorphic StringsEasy
Hash TableString
Solve →
132Time Based Key-Value StoreMedium
Hash TableStringBinary Search
Solve →
133Lowest Common Ancestor of a Binary Tree IIIMedium
Hash TableTwo PointersTree
Solve →
134Permutation in StringMedium
Hash TableTwo PointersString
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135Vertical Order Traversal of a Binary TreeHard
Hash TableTreeDepth-First Search
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136Find All Anagrams in a StringMedium
Hash TableStringSliding Window
Solve →
137Word Ladder IIHard
Hash TableStringBacktracking
Solve →
138Implement Trie (Prefix Tree)Medium
Hash TableStringDesign
Solve →
139Linked List Cycle IIMedium
Hash TableLinked ListTwo Pointers
Solve →
140Intersection of Two Linked ListsEasy
Hash TableLinked ListTwo Pointers
Solve →
141Partition LabelsMedium
Hash TableTwo PointersString
Solve →
142Design In-Memory File SystemHard
Hash TableStringDesign
Solve →
143Clone GraphMedium
Hash TableDepth-First SearchBreadth-First Search
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144Sort Characters By FrequencyMedium
Hash TableStringSorting
Solve →
145Design TwitterMedium
Hash TableLinked ListDesign
Solve →
146Ransom NoteEasy
Hash TableStringCounting
Solve →
147Substring with Concatenation of All WordsHard
Hash TableStringSliding Window
Solve →
148Sum of Beauty of All SubstringsMedium
Hash TableStringCounting
Solve →
149Amount of Time for Binary Tree to Be InfectedMedium
Hash TableTreeDepth-First Search
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150Two Sum IV - Input is a BSTEasy
Hash TableTwo PointersTree
Solve →
151Longest Substring with At Least K Repeating CharactersMedium
Hash TableStringDivide and Conquer
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152Unique Length-3 Palindromic SubsequencesMedium
Hash TableStringBit Manipulation
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153Binary Tree Vertical Order TraversalMedium
Hash TableTreeDepth-First Search
Solve →
154All O`one Data StructureHard
Hash TableLinked ListDesign
Solve →
155Find Longest Self-Contained SubstringHard
Hash TableStringSorting
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156Find the DifferenceEasy
Hash TableStringBit Manipulation
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157Longest PalindromeEasy
Hash TableStringGreedy
Solve →
158Optimal Partition of StringMedium
Hash TableStringGreedy
Solve →
159Design an Array Statistics TrackerHard
Hash TableBinary SearchDesign
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160Repeated DNA SequencesMedium
Hash TableStringBit Manipulation
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161Minimum Genetic MutationMedium
Hash TableStringBreadth-First Search
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162Design File SystemMedium
Hash TableStringDesign
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163Number of Substrings Containing All Three CharactersMedium
Hash TableStringSliding Window
Solve →
164Minimum Number of Pushes to Type Word IIMedium
Hash TableStringGreedy
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165Logger Rate LimiterEasy
Hash TableDesignData Stream
Solve →
166Jewels and StonesEasy
Hash TableString
Solve →
167Maximum Frequency StackHard
Hash TableStackDesign
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168Ugly Number IIMedium
Hash TableMathDynamic Programming
Solve →
169Word PatternEasy
Hash TableString
Solve →
170Custom Sort StringMedium
Hash TableStringSorting
Solve →
171Most Stones Removed with Same Row or ColumnMedium
Hash TableDepth-First SearchUnion-Find
Solve →
172Path CrossingEasy
Hash TableString
Solve →
173Using a Robot to Print the Lexicographically Smallest StringMedium
Hash TableStringStack
Solve →
174Lexicographically Minimum String After Removing StarsMedium
Hash TableStringStack
Solve →
175Longest Substring with At Most K Distinct CharactersMedium
Hash TableStringSliding Window
Solve →
176Find Duplicate SubtreesMedium
Hash TableTreeDepth-First Search
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177Reordered Power of 2Medium
Hash TableMathSorting
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178Substring With Largest VarianceHard
Hash TableStringDynamic Programming
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179Bulls and CowsMedium
Hash TableStringCounting
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180Cousins in Binary Tree IIMedium
Hash TableTreeDepth-First Search
Solve →
181Total Characters in String After Transformations IMedium
Hash TableMathString
Solve →
182Lowest Common Ancestor of a Binary Tree IVMedium
Hash TableTreeDepth-First Search
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183Smallest Number in Infinite SetMedium
Hash TableDesignHeap (Priority Queue)
Solve →
184Maximum Difference Between Even and Odd Frequency IEasy
Hash TableStringCounting
Solve →
185Lexicographically Smallest Permutation Greater Than TargetMedium
Hash TableStringGreedy
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186Fraction to Recurring DecimalMedium
Hash TableMathString
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187Number of AtomsHard
Hash TableStringStack
Solve →
188Clone Binary Tree With Random PointerMedium
Hash TableTreeDepth-First Search
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189Most Frequent Subtree SumMedium
Hash TableTreeDepth-First Search
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190Find the Longest Substring Containing Vowels in Even CountsMedium
Hash TableStringBit Manipulation
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191Count Beautiful Substrings IMedium
Hash TableMathString
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192Rearrange String k Distance ApartHard
Hash TableStringGreedy
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193Encode and Decode TinyURLMedium
Hash TableStringDesign
Solve →
194Design A LeaderboardMedium
Hash TableDesignSorting
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195Design Underground SystemMedium
Hash TableStringDesign
Solve →
196Check if One String Swap Can Make Strings EqualEasy
Hash TableStringCounting
Solve →
197Total Appeal of A StringHard
Hash TableStringDynamic Programming
Solve →
198Decode the MessageEasy
Hash TableString
Solve →
199Take K of Each Character From Left and RightMedium
Hash TableStringSliding Window
Solve →
200Design Log Storage SystemMedium
Hash TableStringDesign
Solve →
201Count Vowel Substrings of a StringEasy
Hash TableString
Solve →
202Minimum Deletions to Make Character Frequencies UniqueMedium
Hash TableStringGreedy
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203Design Task ManagerMedium
Hash TableDesignHeap (Priority Queue)
Solve →
204Longest Balanced Substring IMedium
Hash TableStringCounting
Solve →
205Pyramid Transition MatrixMedium
Hash TableStringBacktracking
Solve →
206Random Pick IndexMedium
Hash TableMathReservoir Sampling
Solve →
207Remove Zero Sum Consecutive Nodes from Linked ListMedium
Hash TableLinked List
Solve →
208Minimum Number of Steps to Make Two Strings AnagramMedium
Hash TableStringCounting
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209Maximum Number of Non-Overlapping SubstringsHard
Hash TableStringGreedy
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210Determine if Two Strings Are CloseMedium
Hash TableStringSorting
Solve →
211Minimum Number of KeypressesMedium
Hash TableStringGreedy
Solve →
212Find Distance in a Binary TreeMedium
Hash TableTreeDepth-First Search
Solve →
213Substrings of Size Three with Distinct CharactersEasy
Hash TableStringSliding Window
Solve →
214Replace Question Marks in String to Minimize Its ValueMedium
Hash TableStringGreedy
Solve →
215Count Number of TextsMedium
Hash TableMathString
Solve →
216Count the Number of Special Characters IEasy
Hash TableString
Solve →
217Stock Price FluctuationMedium
Hash TableDesignHeap (Priority Queue)
Solve →
218HTML Entity ParserMedium
Hash TableString
Solve →
219Dinner Plate StacksHard
Hash TableStackDesign
Solve →
220Uncommon Words from Two SentencesEasy
Hash TableStringCounting
Solve →
221Split a String Into the Max Number of Unique SubstringsMedium
Hash TableStringBacktracking
Solve →
222Number of Good Ways to Split a StringMedium
Hash TableStringDynamic Programming
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223Construct K Palindrome StringsMedium
Hash TableStringGreedy
Solve →
224Data Stream as Disjoint IntervalsHard
Hash TableBinary SearchUnion-Find
Solve →
225Count of Substrings Containing Every Vowel and K Consonants IIMedium
Hash TableStringSliding Window
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226Count Unique Characters of All Substrings of a Given StringHard
Hash TableStringDynamic Programming
Solve →
227Maximum Number of Words You Can TypeEasy
Hash TableString
Solve →
228Check if All Characters Have Equal Number of OccurrencesEasy
Hash TableStringCounting
Solve →
229Check if the Sentence Is PangramEasy
Hash TableString
Solve →
230Find Most Frequent Vowel and ConsonantEasy
Hash TableStringCounting
Solve →
231Longest Balanced Substring IIMedium
Hash TableStringPrefix Sum
Solve →
232Count Largest GroupEasy
Hash TableMathCounting
Solve →
233Find Elements in a Contaminated Binary TreeMedium
Hash TableTreeDepth-First Search
Solve →
234Find Longest Special Substring That Occurs Thrice IMedium
Hash TableStringBinary Search
Solve →
235Find K-Length Substrings With No Repeated CharactersMedium
Hash TableStringSliding Window
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236Clone N-ary TreeMedium
Hash TableTreeDepth-First Search
Solve →
237Count Beautiful Substrings IIHard
Hash TableMathString
Solve →
238Count Numbers With Unique Digits IIEasy
Hash TableMathDynamic Programming
Solve →
239Rearrange Characters to Make Target StringEasy
Hash TableStringCounting
Solve →
240Count the Number of Special Characters IIMedium
Hash TableString
Solve →
241Word Pattern IIMedium
Hash TableStringBacktracking
Solve →
242Minimum Length of String After OperationsMedium
Hash TableStringCounting
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243Minimum Time to Collect All Apples in a TreeMedium
Hash TableTreeDepth-First Search
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244Longest Nice SubstringEasy
Hash TableStringDivide and Conquer
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245Select K Disjoint Special SubstringsMedium
Hash TableStringDynamic Programming
Solve →
246Increasing Decreasing StringEasy
Hash TableStringCounting
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247Smallest Integer Divisible by KMedium
Hash TableMath
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248Longest Substring with At Most Two Distinct CharactersMedium
Hash TableStringSliding Window
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249Longest Subsequence Repeated k TimesHard
Hash TableTwo PointersString
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250Lowest Common Ancestor of Deepest LeavesMedium
Hash TableTreeDepth-First Search
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251Find Valid Pair of Adjacent Digits in StringEasy
Hash TableStringCounting
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252Check If a String Contains All Binary Codes of Size KMedium
Hash TableStringBit Manipulation
Solve →
253Remove Duplicates From an Unsorted Linked ListMedium
Hash TableLinked List
Solve →
254Maximum Number of Occurrences of a SubstringMedium
Hash TableStringSliding Window
Solve →
255Count Substrings That Can Be Rearranged to Contain a String IMedium
Hash TableStringSliding Window
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256Smallest Subtree with all the Deepest NodesMedium
Hash TableTreeDepth-First Search
Solve →
257Buddy StringsEasy
Hash TableString
Solve →
258LRU CacheMedium
Hash TableLinked ListDesign
Solve →
259Longest Substring Without Repeating CharactersMedium
Hash TableStringSliding Window
Solve →
260Reorganize StringMedium
Hash TableStringGreedy
Solve →
261Copy List with Random PointerMedium
Hash TableLinked List
Solve →
262Word LadderHard
Hash TableStringBreadth-First Search
Solve →
263Letter Combinations of a Phone NumberMedium
Hash TableStringBacktracking
Solve →
264Valid AnagramEasy
Hash TableStringSorting
Solve →
265Roman to IntegerEasy
Hash TableMathString
Solve →
266Longest Repeating Character ReplacementMedium
Hash TableStringSliding Window
Solve →
267Minimum Window SubstringHard
Hash TableStringSliding Window
Solve →
268LFU CacheHard
Hash TableLinked ListDesign
Solve →
269All Nodes Distance K in Binary TreeMedium
Hash TableTreeDepth-First Search
Solve →
270First Unique Character in a StringEasy
Hash TableStringQueue
Solve →
271Integer to RomanMedium
Hash TableMathString
Solve →
272Linked List CycleEasy
Hash TableLinked ListTwo Pointers
Solve →
273Happy NumberEasy
Hash TableMathTwo Pointers
Solve →
274Time Based Key-Value StoreMedium
Hash TableStringBinary Search
Solve →
275Isomorphic StringsEasy
Hash TableString
Solve →
276Intersection of Two Linked ListsEasy
Hash TableLinked ListTwo Pointers
Solve →
277Find All Anagrams in a StringMedium
Hash TableStringSliding Window
Solve →
278Word Ladder IIHard
Hash TableStringBacktracking
Solve →
279Vertical Order Traversal of a Binary TreeHard
Hash TableTreeDepth-First Search
Solve →
280Permutation in StringMedium
Hash TableTwo PointersString
Solve →
281Lowest Common Ancestor of a Binary Tree IIIMedium
Hash TableTwo PointersTree
Solve →
282Linked List Cycle IIMedium
Hash TableLinked ListTwo Pointers
Solve →
283Partition LabelsMedium
Hash TableTwo PointersString
Solve →
284Sort Characters By FrequencyMedium
Hash TableStringSorting
Solve →
285Design TwitterMedium
Hash TableLinked ListDesign
Solve →
286Implement Trie (Prefix Tree)Medium
Hash TableStringDesign
Solve →
287Clone GraphMedium
Hash TableDepth-First SearchBreadth-First Search
Solve →
288Ransom NoteEasy
Hash TableStringCounting
Solve →
289Design In-Memory File SystemHard
Hash TableStringDesign
Solve →
290Amount of Time for Binary Tree to Be InfectedMedium
Hash TableTreeDepth-First Search
Solve →
291Jewels and StonesEasy
Hash TableString
Solve →
292Find Longest Self-Contained SubstringHard
Hash TableStringSorting
Solve →
293Substring with Concatenation of All WordsHard
Hash TableStringSliding Window
Solve →
294Minimum Number of Pushes to Type Word IIMedium
Hash TableStringGreedy
Solve →
295Longest Substring with At Least K Repeating CharactersMedium
Hash TableStringDivide and Conquer
Solve →
296Two Sum IV - Input is a BSTEasy
Hash TableTwo PointersTree
Solve →
297Substring With Largest VarianceHard
Hash TableStringDynamic Programming
Solve →
298Using a Robot to Print the Lexicographically Smallest StringMedium
Hash TableStringStack
Solve →
299Custom Sort StringMedium
Hash TableStringSorting
Solve →
300Path CrossingEasy
Hash TableString
Solve →
301Sum of Beauty of All SubstringsMedium
Hash TableStringCounting
Solve →
302Cousins in Binary Tree IIMedium
Hash TableTreeDepth-First Search
Solve →
303Find the DifferenceEasy
Hash TableStringBit Manipulation
Solve →
304All O`one Data StructureHard
Hash TableLinked ListDesign
Solve →
305Most Frequent Subtree SumMedium
Hash TableTreeDepth-First Search
Solve →
306Clone Binary Tree With Random PointerMedium
Hash TableTreeDepth-First Search
Solve →
307Lowest Common Ancestor of a Binary Tree IVMedium
Hash TableTreeDepth-First Search
Solve →
308Total Appeal of A StringHard
Hash TableStringDynamic Programming
Solve →
309Smallest Number in Infinite SetMedium
Hash TableDesignHeap (Priority Queue)
Solve →
310Count the Number of Special Characters IEasy
Hash TableString
Solve →
311Repeated DNA SequencesMedium
Hash TableStringBit Manipulation
Solve →
312Encode and Decode TinyURLMedium
Hash TableStringDesign
Solve →
313Most Stones Removed with Same Row or ColumnMedium
Hash TableDepth-First SearchUnion-Find
Solve →
314Unique Length-3 Palindromic SubsequencesMedium
Hash TableStringBit Manipulation
Solve →
315Optimal Partition of StringMedium
Hash TableStringGreedy
Solve →
316Count Beautiful Substrings IMedium
Hash TableMathString
Solve →
317Binary Tree Vertical Order TraversalMedium
Hash TableTreeDepth-First Search
Solve →
318Logger Rate LimiterEasy
Hash TableDesignData Stream
Solve →
319Longest PalindromeEasy
Hash TableStringGreedy
Solve →
320Minimum Genetic MutationMedium
Hash TableStringBreadth-First Search
Solve →
321Design File SystemMedium
Hash TableStringDesign
Solve →
322Count Number of TextsMedium
Hash TableMathString
Solve →
323Maximum Frequency StackHard
Hash TableStackDesign
Solve →
324Maximum Number of Non-Overlapping SubstringsHard
Hash TableStringGreedy
Solve →
325Find Distance in a Binary TreeMedium
Hash TableTreeDepth-First Search
Solve →
326Minimum Number of KeypressesMedium
Hash TableStringGreedy
Solve →
327Replace Question Marks in String to Minimize Its ValueMedium
Hash TableStringGreedy
Solve →
328Design an Array Statistics TrackerHard
Hash TableBinary SearchDesign
Solve →
329Word PatternEasy
Hash TableString
Solve →
330Bulls and CowsMedium
Hash TableStringCounting
Solve →
331Find K-Length Substrings With No Repeated CharactersMedium
Hash TableStringSliding Window
Solve →
332Number of Substrings Containing All Three CharactersMedium
Hash TableStringSliding Window
Solve →
333Clone N-ary TreeMedium
Hash TableTreeDepth-First Search
Solve →
334Rearrange Characters to Make Target StringEasy
Hash TableStringCounting
Solve →
335Count Beautiful Substrings IIHard
Hash TableMathString
Solve →
336Count Numbers With Unique Digits IIEasy
Hash TableMathDynamic Programming
Solve →
337Count the Number of Special Characters IIMedium
Hash TableString
Solve →
338Ugly Number IIMedium
Hash TableMathDynamic Programming
Solve →
339Find Duplicate SubtreesMedium
Hash TableTreeDepth-First Search
Solve →
340Lexicographically Minimum String After Removing StarsMedium
Hash TableStringStack
Solve →
341Longest Substring with At Most K Distinct CharactersMedium
Hash TableStringSliding Window
Solve →
342Number of AtomsHard
Hash TableStringStack
Solve →
343Reordered Power of 2Medium
Hash TableMathSorting
Solve →
344Total Characters in String After Transformations IMedium
Hash TableMathString
Solve →
345Lexicographically Smallest Permutation Greater Than TargetMedium
Hash TableStringGreedy
Solve →
346Longest Balanced Substring IMedium
Hash TableStringCounting
Solve →
347Maximum Difference Between Even and Odd Frequency IEasy
Hash TableStringCounting
Solve →
348Design Task ManagerMedium
Hash TableDesignHeap (Priority Queue)
Solve →
349Fraction to Recurring DecimalMedium
Hash TableMathString
Solve →
350Check if the Sentence Is PangramEasy
Hash TableString
Solve →
351Find the Longest Substring Containing Vowels in Even CountsMedium
Hash TableStringBit Manipulation
Solve →
352Rearrange String k Distance ApartHard
Hash TableStringGreedy
Solve →
353Take K of Each Character From Left and RightMedium
Hash TableStringSliding Window
Solve →
354Count Vowel Substrings of a StringEasy
Hash TableString
Solve →
355Pyramid Transition MatrixMedium
Hash TableStringBacktracking
Solve →
356Longest Balanced Substring IIMedium
Hash TableStringPrefix Sum
Solve →
357Check If a String Contains All Binary Codes of Size KMedium
Hash TableStringBit Manipulation
Solve →
358Buddy StringsEasy
Hash TableString
Solve →
359Design A LeaderboardMedium
Hash TableDesignSorting
Solve →
360Design Underground SystemMedium
Hash TableStringDesign
Solve →
361Minimum Deletions to Make Character Frequencies UniqueMedium
Hash TableStringGreedy
Solve →
362Check if One String Swap Can Make Strings EqualEasy
Hash TableStringCounting
Solve →
363Substrings of Size Three with Distinct CharactersEasy
Hash TableStringSliding Window
Solve →
364Decode the MessageEasy
Hash TableString
Solve →
365Number of Good Ways to Split a StringMedium
Hash TableStringDynamic Programming
Solve →
366Design Log Storage SystemMedium
Hash TableStringDesign
Solve →
367Stock Price FluctuationMedium
Hash TableDesignHeap (Priority Queue)
Solve →
368Largest Palindromic NumberMedium
Hash TableStringGreedy
Solve →
369Maximum Number of BalloonsEasy
Hash TableStringCounting
Solve →
370Random Pick IndexMedium
Hash TableMathReservoir Sampling
Solve →
371Count Unique Characters of All Substrings of a Given StringHard
Hash TableStringDynamic Programming
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372Remove Zero Sum Consecutive Nodes from Linked ListMedium
Hash TableLinked List
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373Minimum Number of Steps to Make Two Strings AnagramMedium
Hash TableStringCounting
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374Determine if Two Strings Are CloseMedium
Hash TableStringSorting
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375HTML Entity ParserMedium
Hash TableString
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376Dinner Plate StacksHard
Hash TableStackDesign
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377Uncommon Words from Two SentencesEasy
Hash TableStringCounting
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378Split a String Into the Max Number of Unique SubstringsMedium
Hash TableStringBacktracking
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379Construct K Palindrome StringsMedium
Hash TableStringGreedy
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380Minimum Time to Collect All Apples in a TreeMedium
Hash TableTreeDepth-First Search
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381Data Stream as Disjoint IntervalsHard
Hash TableBinary SearchUnion-Find
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382Count of Substrings Containing Every Vowel and K Consonants IIMedium
Hash TableStringSliding Window
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383Check if All Characters Have Equal Number of OccurrencesEasy
Hash TableStringCounting
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384Longest Nice SubstringEasy
Hash TableStringDivide and Conquer
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385Maximum Number of Occurrences of a SubstringMedium
Hash TableStringSliding Window
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386Find Most Frequent Vowel and ConsonantEasy
Hash TableStringCounting
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387Maximum Number of Words You Can TypeEasy
Hash TableString
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388Smallest Integer Divisible by KMedium
Hash TableMath
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389Count Largest GroupEasy
Hash TableMathCounting
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390Longest Substring with At Most Two Distinct CharactersMedium
Hash TableStringSliding Window
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391Lowest Common Ancestor of Deepest LeavesMedium
Hash TableTreeDepth-First Search
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392Find Elements in a Contaminated Binary TreeMedium
Hash TableTreeDepth-First Search
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393Word Pattern IIMedium
Hash TableStringBacktracking
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394Find Longest Special Substring That Occurs Thrice IMedium
Hash TableStringBinary Search
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395Minimum Length of String After OperationsMedium
Hash TableStringCounting
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396Select K Disjoint Special SubstringsMedium
Hash TableStringDynamic Programming
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397Longest Subsequence Repeated k TimesHard
Hash TableTwo PointersString
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398Increasing Decreasing StringEasy
Hash TableStringCounting
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399Find Valid Pair of Adjacent Digits in StringEasy
Hash TableStringCounting
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400Remove Duplicates From an Unsorted Linked ListMedium
Hash TableLinked List
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401Count Substrings That Can Be Rearranged to Contain a String IMedium
Hash TableStringSliding Window
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402Smallest Subtree with all the Deepest NodesMedium
Hash TableTreeDepth-First Search
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403Implement Trie II (Prefix Tree)Medium
Hash TableStringDesign
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404Check if Strings Can be Made Equal With Operations IIMedium
Hash TableStringSorting
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405Largest Color Value in a Directed GraphHard
Hash TableStringDynamic Programming
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406K-Similar StringsHard
Hash TableStringBreadth-First Search
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407Find Mirror Score of a StringMedium
Hash TableStringStack
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