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Top Interview 150Official

LeetCode's curated list of 150 must-do problems for coding interviews. Covers all essential patterns with increasing difficulty.

By FleetCode150 problems39 Easy93 Medium18 HardUpdated 23 Mar 2026

Start: Merge Sorted Array

150problems

39Easy

93Medium

18Hard

Signed in, the sheet shows which of these you have solved.

TitleSolutionAcceptDifficultyTopics

88. Merge Sorted ArrayVideo

Solution55.7%Easy

Array, Sorting +1· 37 companies

27. Remove ElementVideo

Solution62.2%Easy

Array, Two Pointers· 10 companies

26. Remove Duplicates from Sorted ArrayVideo

Solution63.7%Easy

Array, Two Pointers· 26 companies

80. Remove Duplicates from Sorted Array IIVideo

Solution65.0%Medium

Array, Two Pointers· 9 companies

169. Majority ElementVideo

Solution66.2%Easy

Array, Counting +3· 22 companies

189. Rotate ArrayVideo

Solution45.3%Medium

Array, Math +1· 27 companies

121. Best Time to Buy and Sell StockVideo

Solution57.1%Easy

Array, Dynamic Programming· 92 companies

122. Best Time to Buy and Sell Stock IIVideo

Solution71.4%Medium

Array, Dynamic Programming +1· 28 companies

55. Jump GameVideo

Solution41.2%Medium

Array, Dynamic Programming +1· 33 companies

45. Jump Game IIVideo

Solution43.2%Medium

Array, Dynamic Programming +1· 26 companies

274. H-IndexVideo

Solution41.8%Medium

Array, Counting Sort +1· 8 companies

380. Insert Delete GetRandom O(1)Video

Solution55.3%Medium

Array, Design +3· 38 companies

238. Product of Array Except SelfVideo

Solution69.3%Medium

Array, Prefix Sum· 40 companies

134. Gas StationVideo

Solution48.4%Medium

Array, Greedy· 29 companies

135. CandyVideo

Solution49.3%Hard

Array, Greedy· 24 companies

42. Trapping Rain WaterVideo

Solution68.2%Hard

Array, Dynamic Programming +3· 73 companies

13. Roman to IntegerVideo

Solution67.0%Easy

Hash Table, Math +1· 36 companies

12. Integer to RomanVideo

Solution71.8%Medium

Hash Table, Math +1· 31 companies

58. Length of Last WordVideo

Solution59.7%Easy

String· 7 companies

14. Longest Common PrefixVideo

Solution48.6%Easy

String, Trie· 60 companies

151. Reverse Words in a StringVideo

Solution57.8%Medium

String, Two Pointers· 30 companies

6. Zigzag ConversionVideo

Solution54.9%Medium

String· 19 companies

28. Find the Index of the First Occurrence in a StringVideo

Solution47.0%Easy

String, String Matching +1· 16 companies

68. Text JustificationVideo

Solution52.4%Hard

Array, Simulation +1· 44 companies

125. Valid PalindromeVideo

Solution54.2%Easy

String, Two Pointers· 39 companies

392. Is SubsequenceVideo

Solution49.5%Easy

Dynamic Programming, String +1· 16 companies

167. Two Sum II - Input Array Is SortedVideo

Solution66.1%Medium

Array, Binary Search +1· 16 companies

11. Container With Most WaterVideo

Solution60.9%Medium

Array, Greedy +1· 57 companies

15. 3SumVideo

Solution40.1%Medium

Array, Sorting +1· 57 companies

209. Minimum Size Subarray SumVideo

Solution53.1%Medium

Array, Binary Search +2· 18 companies

3. Longest Substring Without Repeating CharactersVideo

Solution39.9%Medium

Hash Table, Sliding Window +1· 104 companies

30. Substring with Concatenation of All WordsVideo

Solution35.4%Hard

Hash Table, Sliding Window +1· 10 companies

76. Minimum Window SubstringVideo

Solution48.3%Hard

Hash Table, Sliding Window +1· 35 companies

36. Valid SudokuVideo

Solution64.9%Medium

Array, Hash Table +1· 26 companies

54. Spiral MatrixVideo

Solution58.2%Medium

Array, Matrix +1· 49 companies

48. Rotate ImageVideo

Solution80.7%Medium

Array, Math +1· 36 companies

73. Set Matrix ZeroesVideo

Solution63.8%Medium

Array, Hash Table +1· 22 companies

289. Game of LifeVideo

Solution73.0%Medium

Array, Matrix +1· 15 companies

383. Ransom NoteVideo

Solution66.3%Easy

Counting, Hash Table +1· 14 companies

205. Isomorphic StringsVideo

Solution48.8%Easy

Hash Table, String· 15 companies

290. Word PatternVideo

Solution44.5%Easy

Hash Table, String· 9 companies

242. Valid AnagramVideo

Solution68.5%Easy

Hash Table, Sorting +1· 40 companies

49. Group AnagramsVideo

Solution73.0%Medium

Array, Hash Table +2· 87 companies

1. Two SumVideo

Solution57.8%Easy

Array, Hash Table· 127 companies

202. Happy NumberVideo

Solution60.0%Easy

Hash Table, Math +1· 27 companies

219. Contains Duplicate IIVideo

Solution51.6%Easy

Array, Hash Table +1· 15 companies

128. Longest Consecutive SequenceVideo

Solution47.0%Medium

Array, Hash Table +1· 40 companies

228. Summary RangesVideo

Solution54.6%Easy

Array· 9 companies

56. Merge IntervalsVideo

Solution52.6%Medium

Array, Sorting· 112 companies

57. Insert IntervalVideo

Solution46.1%Medium

Array· 16 companies

452. Minimum Number of Arrows to Burst BalloonsVideo

Solution61.9%Medium

Array, Greedy +1· 8 companies

20. Valid ParenthesesVideo

Solution45.2%Easy

Stack, String· 113 companies

71. Simplify PathVideo

Solution51.4%Medium

Stack, String· 24 companies

155. Min StackVideo

Solution58.5%Medium

Design, Stack· 37 companies

150. Evaluate Reverse Polish NotationVideo

Solution58.5%Medium

Array, Math +1· 18 companies

224. Basic CalculatorVideo

Solution47.3%Hard

Math, Recursion +2· 25 companies

141. Linked List CycleVideo

Solution55.2%Easy

Hash Table, Linked List +1· 24 companies

2. Add Two NumbersVideo

Solution49.3%Medium

Linked List, Math +1· 37 companies

21. Merge Two Sorted ListsVideo

Solution68.7%Easy

Linked List, Recursion· 36 companies

138. Copy List with Random PointerVideo

Solution63.8%Medium

Hash Table, Linked List· 22 companies

92. Reverse Linked List IIVideo

Solution52.4%Medium

Linked List· 16 companies

25. Reverse Nodes in k-GroupVideo

Solution67.4%Hard

Linked List, Recursion· 27 companies

19. Remove Nth Node From End of ListVideo

Solution52.4%Medium

Linked List, Two Pointers· 18 companies

82. Remove Duplicates from Sorted List IIVideo

Solution52.8%Medium

Linked List, Two Pointers· 11 companies

61. Rotate ListVideo

Solution43.1%Medium

Linked List, Two Pointers· 9 companies

86. Partition ListVideo

Solution62.0%Medium

Linked List, Two Pointers· 5 companies

146. LRU CacheVideo

Solution48.2%Medium

Design, Doubly-Linked List +2· 120 companies

104. Maximum Depth of Binary TreeVideo

Solution78.6%Easy

Binary Tree, Breadth-First Search +2· 17 companies

100. Same TreeVideo

Solution68.0%Easy

Binary Tree, Breadth-First Search +2· 9 companies

226. Invert Binary TreeVideo

Solution80.5%Easy

Binary Tree, Breadth-First Search +2· 9 companies

101. Symmetric TreeVideo

Solution62.1%Easy

Binary Tree, Breadth-First Search +2· 11 companies

105. Construct Binary Tree from Preorder and Inorder TraversalVideo

Solution69.7%Medium

Array, Binary Tree +3· 9 companies

106. Construct Binary Tree from Inorder and Postorder TraversalVideo

Solution69.4%Medium

Array, Binary Tree +3· 7 companies

117. Populating Next Right Pointers in Each Node IIVideo

Solution57.9%Medium

Binary Tree, Breadth-First Search +3· 7 companies

114. Flatten Binary Tree to Linked ListVideo

Solution71.6%Medium

Binary Tree, Depth-First Search +3· 8 companies

112. Path SumVideo

Solution55.8%Easy

Binary Tree, Breadth-First Search +2· 9 companies

129. Sum Root to Leaf NumbersVideo

Solution70.3%Medium

Binary Tree, Depth-First Search +1· 7 companies

124. Binary Tree Maximum Path SumVideo

Solution42.7%Hard

Binary Tree, Depth-First Search +2· 25 companies

173. Binary Search Tree IteratorVideo

Solution76.9%Medium

Binary Search Tree, Binary Tree +4· 8 companies

222. Count Complete Tree NodesVideo

Solution72.6%Medium

Binary Search, Binary Tree +2· 7 companies

236. Lowest Common Ancestor of a Binary TreeVideo

Solution70.1%Medium

Binary Tree, Depth-First Search +1· 22 companies

199. Binary Tree Right Side ViewVideo

Solution71.5%Medium

Binary Tree, Breadth-First Search +2· 14 companies

637. Average of Levels in Binary TreeVideo

Solution74.8%Easy

Binary Tree, Breadth-First Search +2· 4 companies

102. Binary Tree Level Order TraversalVideo

Solution73.5%Medium

Binary Tree, Breadth-First Search +1· 16 companies

103. Binary Tree Zigzag Level Order TraversalVideo

Solution64.4%Medium

Binary Tree, Breadth-First Search +1· 19 companies

530. Minimum Absolute Difference in BSTVideo

Solution59.3%Easy

Binary Search Tree, Binary Tree +3· 3 companies

230. Kth Smallest Element in a BSTVideo

Solution77.2%Medium

Binary Search Tree, Binary Tree +2· 12 companies

98. Validate Binary Search TreeVideo

Solution36.1%Medium

Binary Search Tree, Binary Tree +2· 18 companies

200. Number of IslandsVideo

Solution65.2%Medium

Array, Breadth-First Search +3· 86 companies

130. Surrounded RegionsVideo

Solution46.1%Medium

Array, Breadth-First Search +3· 12 companies

133. Clone GraphVideo

Solution66.1%Medium

Breadth-First Search, Depth-First Search +2· 18 companies

399. Evaluate DivisionVideo

Solution64.7%Medium

Array, Breadth-First Search +5· 23 companies

207. Course ScheduleVideo

Solution52.2%Medium

Breadth-First Search, Depth-First Search +2· 45 companies

210. Course Schedule IIVideo

Solution56.3%Medium

Breadth-First Search, Depth-First Search +2· 36 companies

909. Snakes and LaddersVideo

Solution48.0%Medium

Array, Breadth-First Search +1· 12 companies

433. Minimum Genetic MutationVideo

Solution57.1%Medium

Breadth-First Search, Hash Table +1· 6 companies

127. Word LadderVideo

Solution46.3%Hard

Breadth-First Search, Hash Table +1· 41 companies

208. Implement Trie (Prefix Tree)Video

Solution69.9%Medium

Design, Hash Table +2· 21 companies

211. Design Add and Search Words Data StructureVideo

Solution48.9%Medium

Depth-First Search, Design +2· 13 companies

212. Word Search IIVideo

Solution38.8%Hard

Array, Backtracking +3· 21 companies

17. Letter Combinations of a Phone NumberVideo

Solution66.9%Medium

Backtracking, Hash Table +1· 34 companies

77. CombinationsVideo

Solution74.9%Medium

Backtracking· 8 companies

46. PermutationsVideo

Solution82.3%Medium

Array, Backtracking· 25 companies

39. Combination SumVideo

Solution76.9%Medium

Array, Backtracking· 26 companies

52. N-Queens IIVideo

Solution79.5%Hard

Backtracking· 10 companies

22. Generate ParenthesesVideo

Solution79.6%Medium

Backtracking, Dynamic Programming +1· 40 companies

79. Word SearchVideo

Solution48.2%Medium

Array, Backtracking +2· 36 companies

108. Convert Sorted Array to Binary Search TreeVideo

Solution75.9%Easy

Array, Binary Search Tree +3· 9 companies

148. Sort ListVideo

Solution65.2%Medium

Divide and Conquer, Linked List +3· 9 companies

427. Construct Quad TreeVideo

Solution78.8%Medium

Array, Divide and Conquer +2· 8 companies

23. Merge k Sorted ListsVideo

Solution60.3%Hard

Divide and Conquer, Heap (Priority Queue) +2· 50 companies

53. Maximum SubarrayVideo

Solution53.7%Medium

Array, Divide and Conquer +1· 64 companies

918. Maximum Sum Circular SubarrayVideo

Solution51.5%Medium

Array, Divide and Conquer +3· 12 companies

35. Search Insert PositionVideo

Solution52.1%Easy

Array, Binary Search· 12 companies

74. Search a 2D MatrixVideo

Solution54.4%Medium

Array, Binary Search +1· 19 companies

162. Find Peak ElementVideo

Solution46.8%Medium

Array, Binary Search· 30 companies

33. Search in Rotated Sorted ArrayVideo

Solution45.5%Medium

Array, Binary Search· 53 companies

34. Find First and Last Position of Element in Sorted ArrayVideo

Solution49.7%Medium

Array, Binary Search· 29 companies

153. Find Minimum in Rotated Sorted ArrayVideo

Solution55.3%Medium

Array, Binary Search· 18 companies

4. Median of Two Sorted ArraysVideo

Solution47.9%Hard

Array, Binary Search +1· 45 companies

215. Kth Largest Element in an ArrayVideo

Solution69.4%Medium

Array, Divide and Conquer +3· 41 companies

502. IPOVideo

Solution53.6%Hard

Array, Greedy +2· 9 companies

373. Find K Pairs with Smallest SumsVideo

Solution42.3%Medium

Array, Heap (Priority Queue)· 10 companies

295. Find Median from Data StreamVideo

Solution54.9%Hard

Data Stream, Design +3· 40 companies

67. Add BinaryVideo

Solution58.4%Easy

Bit Manipulation, Math +2· 17 companies

190. Reverse BitsVideo

Solution69.2%Easy

Bit Manipulation, Divide and Conquer· 9 companies

191. Number of 1 BitsVideo

Solution77.7%Easy

Bit Manipulation, Divide and Conquer· 11 companies

136. Single NumberVideo

Solution78.1%Easy

Array, Bit Manipulation· 15 companies

137. Single Number IIVideo

Solution68.0%Medium

Array, Bit Manipulation· 5 companies

201. Bitwise AND of Numbers RangeVideo

Solution49.4%Medium

Bit Manipulation· 5 companies

70. Climbing StairsVideo

Solution54.0%Easy

Dynamic Programming, Math +1· 37 companies

198. House RobberVideo

Solution53.6%Medium

Array, Dynamic Programming· 40 companies

139. Word BreakVideo

Solution49.8%Medium

Array, Dynamic Programming +4· 32 companies

322. Coin ChangeVideo

Solution49.3%Medium

Array, Breadth-First Search +1· 40 companies

300. Longest Increasing SubsequenceVideo

Solution59.8%Medium

Array, Binary Search +1· 30 companies

120. TriangleVideo

Solution59.9%Medium

Array, Dynamic Programming· 11 companies

64. Minimum Path SumVideo

Solution68.6%Medium

Array, Dynamic Programming +1· 17 companies

63. Unique Paths IIVideo

Solution44.9%Medium

Array, Dynamic Programming +1· 9 companies

5. Longest Palindromic SubstringVideo

Solution38.7%Medium

Dynamic Programming, String +1· 81 companies

97. Interleaving StringVideo

Solution45.0%Medium

Dynamic Programming, String· 10 companies

72. Edit DistanceVideo

Solution61.5%Medium

Dynamic Programming, String· 24 companies

123. Best Time to Buy and Sell Stock IIIVideo

Solution54.5%Hard

Array, Dynamic Programming· 13 companies

188. Best Time to Buy and Sell Stock IVVideo

Solution51.5%Hard

Array, Dynamic Programming· 11 companies

221. Maximal SquareVideo

Solution50.7%Medium

Array, Dynamic Programming +1· 28 companies

9. Palindrome NumberVideo

Solution61.0%Easy

Math· 31 companies

66. Plus OneVideo

Solution50.3%Easy

Array, Math· 13 companies

172. Factorial Trailing ZeroesVideo

Solution47.5%Medium

Math· 5 companies

69. Sqrt(x)Video

Solution42.2%Easy

Binary Search, Math· 17 companies

50. Pow(x, n)Video

Solution39.0%Medium

Math, Recursion· 22 companies

149. Max Points on a LineVideo

Solution31.6%Hard

Array, Geometry +2· 16 companies

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