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List · 150 problems

NeetCode 150: All 150 Problems in a Study Order

One hundred fifty problems is a long road. I walk it one topic at a time, so each step builds on the last. The order is mine. I start with the openers, then go one topic at a time, easiest first.

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Whose list this is

NeetCode built the NeetCode 150. StrongYes did not write it, and the problems belong to their sources. Every problem below opens a StrongYes practice page for the problem with the same name. Source: NeetCode.

The problems, in my order

28 easy · 101 medium · 21 hard. Solved marks come from this browser and, signed in, your account.

  1. Contains DuplicateeasyArrays & Hashing
  2. Plus OneeasyArrays & Hashing
  3. Valid AnagrameasyStringsArrays & Hashing
  4. Happy NumbereasyTwo PointersArrays & Hashing
  5. Two SumeasyTwo PointersArrays & Hashing
  6. Valid PalindromeeasyTwo PointersStrings
  7. Detect SquaresmediumDesignArrays & Hashing
  8. Group AnagramsmediumStringsArrays & Hashing
  9. Product of Array Except SelfmediumArrays & Hashing
  10. Rotate ImagemediumArrays & Hashing
  11. Set Matrix ZeroesmediumArrays & Hashing
  12. Spiral MatrixmediumArrays & Hashing
  13. Valid SudokumediumArrays & Hashing
  14. 3SummediumTwo PointersArrays & Hashing
  15. Two Sum II - Input Array Is SortedmediumTwo PointersArrays & Hashing
  16. Valid ParentheseseasyStackStrings
  17. Car FleetmediumStackArrays & Hashing
  18. Daily TemperaturesmediumStackArrays & Hashing
  19. Evaluate Reverse Polish NotationmediumStackArrays & Hashing
  20. Min StackmediumStackDesign
  21. Largest Rectangle in HistogramhardStackArrays & Hashing
  22. Binary SearcheasyBinary SearchArrays & Hashing
  23. Find Minimum in Rotated Sorted ArraymediumBinary SearchArrays & Hashing
  24. Koko Eating BananasmediumBinary SearchArrays & Hashing
  25. Search a 2D MatrixmediumBinary SearchArrays & Hashing
  26. Search in Rotated Sorted ArraymediumBinary SearchArrays & Hashing
  27. Time Based Key-Value StoremediumBinary SearchDesign
  28. Median of Two Sorted ArrayshardBinary SearchArrays & Hashing
  29. Best Time to Buy and Sell StockeasySliding WindowArrays & Hashing
  30. Analytics: Longest Unique Session WindowmediumSliding WindowStrings
  31. Longest Repeating Character ReplacementmediumSliding WindowTwo Pointers
  32. Permutation in StringmediumSliding WindowTwo Pointers
  33. Minimum Window SubstringhardSliding WindowStrings
  34. Linked List CycleeasyLinked ListsTwo Pointers
  35. Merge Two Sorted ListseasyLinked Lists
  36. Reverse Linked ListeasyLinked Lists
  37. Add Two NumbersmediumLinked Lists
  38. Copy List with Random PointermediumLinked ListsArrays & Hashing
  39. LRU CachemediumLinked ListsDesign
  40. Remove Nth Node From End of ListmediumLinked ListsTwo Pointers
  41. Reorder ListmediumLinked ListsStack
  42. Reverse Nodes in k-GrouphardLinked Lists
  43. Implement Trie (Prefix Tree)mediumTreesDesign
  44. Balanced Binary TreeeasyTreesBFS & DFS
  45. Diameter of Binary TreeeasyTreesBFS & DFS
  46. Invert Binary TreeeasyTreesBFS & DFS
  47. Maximum Depth of Binary TreeeasyTreesBFS & DFS
  48. Same TreeeasyTreesBFS & DFS
  49. Subtree of Another TreeeasyTreesStrings
  50. Binary Tree Level Order TraversalmediumTreesBFS & DFS
  51. Binary Tree Right Side ViewmediumTreesBFS & DFS
  52. Construct Binary Tree from Preorder and Inorder TraversalmediumTreesBFS & DFS
  53. Count Good Nodes in Binary TreemediumTreesBFS & DFS
  54. Design Add and Search Words Data StructuremediumTreesDesign
  55. Kth Smallest Element in a BSTmediumTreesBFS & DFS
  56. Lowest Common Ancestor of a Binary Search TreemediumTreesBFS & DFS
  57. Validate Binary Search TreemediumTreesBFS & DFS
  58. Serialize and Deserialize Binary TreehardTreesDesign
  59. Kth Largest Element in a StreameasyHeapsTrees
  60. Last Stone WeighteasyHeapsArrays & Hashing
  61. Design TwittermediumLinked ListsHeaps
  62. K Closest Points to OriginmediumBinary SearchHeaps
  63. Kth Largest Element in an ArraymediumBinary SearchHeaps
  64. Telemetry: Top K Frequent Error CodesmediumHeapsArrays & Hashing
  65. Find Median from Data StreamhardHeapsTwo Pointers
  66. Merge K Sorted ListshardLinked ListsHeaps
  67. Sliding Window MaximumhardSliding WindowStack
  68. Combination SummediumBacktrackingArrays & Hashing
  69. Combination Sum IImediumBacktrackingArrays & Hashing
  70. Letter Combinations of a Phone NumbermediumBacktrackingStrings
  71. PermutationsmediumBacktrackingArrays & Hashing
  72. Word SearchmediumBacktrackingStrings
  73. N-QueenshardBacktrackingArrays & Hashing
  74. Word Search IIhardBacktrackingTrees
  75. Clone GraphmediumGraphsBFS & DFS
  76. Course SchedulemediumHeapsGraphs
  77. Course Schedule IImediumGraphsBFS & DFS
  78. Graph Valid TreemediumGraphsBFS & DFS
  79. Longest Consecutive SequencemediumGraphsArrays & Hashing
  80. Max Area of IslandmediumGraphsBFS & DFS
  81. Network Delay TimemediumHeapsGraphs
  82. Number of Connected Components in an Undirected GraphmediumGraphsBFS & DFS
  83. Number of IslandsmediumGraphsBFS & DFS
  84. Pacific Atlantic Water FlowmediumGraphsBFS & DFS
  85. Redundant ConnectionmediumGraphsBFS & DFS
  86. Rotting OrangesmediumGraphsBFS & DFS
  87. Surrounded RegionsmediumGraphsBFS & DFS
  88. Walls and GatesmediumGraphsBFS & DFS
  89. Alien DictionaryhardGraphsStrings
  90. Reconstruct ItineraryhardBacktrackingGraphs
  91. Swim in Rising WaterhardBinary SearchHeaps
  92. Word LadderhardGraphsStrings
  93. Climbing StairseasyDynamic Programming
  94. Min Cost Climbing StairseasyDynamic ProgrammingArrays & Hashing
  95. Cheapest Flights Within K StopsmediumHeapsGraphs
  96. Coin ChangemediumDynamic ProgrammingBFS & DFS
  97. Coin Change IImediumDynamic ProgrammingArrays & Hashing
  98. Decode WaysmediumDynamic ProgrammingStrings
  99. Edit DistancemediumDynamic ProgrammingStrings
  100. Equal Sum Array PartitionmediumDynamic ProgrammingArrays & Hashing
  101. Generate ParenthesesmediumBacktrackingDynamic Programming
  102. House RobbermediumDynamic ProgrammingArrays & Hashing
  103. House Robber IImediumDynamic ProgrammingArrays & Hashing
  104. Interleaving StringmediumDynamic ProgrammingStrings
  105. Longest Common SubsequencemediumDynamic ProgrammingStrings
  106. Longest Increasing SubsequencemediumBinary SearchDynamic Programming
  107. Longest Palindromic SubstringmediumTwo PointersDynamic Programming
  108. Maximum Product SubarraymediumDynamic ProgrammingArrays & Hashing
  109. Maximum SubarraymediumDynamic ProgrammingArrays & Hashing
  110. Palindrome PartitioningmediumBacktrackingDynamic Programming
  111. Palindromic SubstringsmediumTwo PointersDynamic Programming
  112. Stock Trading with CooldownmediumDynamic ProgrammingArrays & Hashing
  113. Target SummediumBacktrackingDynamic Programming
  114. Unique PathsmediumDynamic Programming
  115. Word BreakmediumTreesDynamic Programming
  116. Binary Tree Maximum Path SumhardTreesDynamic Programming
  117. Burst BalloonshardDynamic ProgrammingArrays & Hashing
  118. Distinct SubsequenceshardDynamic ProgrammingStrings
  119. Longest Increasing Path in a MatrixhardGraphsDynamic Programming
  120. Regular Expression MatchinghardBacktrackingDynamic Programming
  121. Trapping Rain WaterhardStackHeaps
  122. Container With Most WatermediumGreedyTwo Pointers
  123. Gas StationmediumGreedyArrays & Hashing
  124. Hand of StraightsmediumGreedyArrays & Hashing
  125. Jump GamemediumGreedyDynamic Programming
  126. Jump Game IImediumGreedyDynamic Programming
  127. Merge Triplets to Form Target TripletmediumGreedyArrays & Hashing
  128. Min Cost to Connect All PointsmediumGreedyHeaps
  129. Partition LabelsmediumGreedyTwo Pointers
  130. Task SchedulermediumGreedyHeaps
  131. Valid Parenthesis StringmediumStackGreedy
  132. Meeting RoomseasyIntervalsGreedy
  133. Insert IntervalmediumIntervalsArrays & Hashing
  134. Meeting Rooms IImediumIntervalsGreedy
  135. Merge IntervalsmediumIntervalsArrays & Hashing
  136. Non-overlapping IntervalsmediumIntervalsGreedy
  137. Minimum Interval to Include Each QueryhardIntervalsBinary Search
  138. Multiply StringsmediumStrings
  139. Pow(x, n)medium
  140. Reverse Integermedium
  141. Counting BitseasyBit ManipulationDynamic Programming
  142. Missing NumbereasyBit ManipulationBinary Search
  143. Number of 1 BitseasyBit Manipulation
  144. Reverse BitseasyBit Manipulation
  145. Single NumbereasyBit ManipulationArrays & Hashing
  146. Find the Duplicate NumbermediumBit ManipulationBinary Search
  147. SubsetsmediumBit ManipulationBacktracking
  148. Subsets IImediumBit ManipulationBacktracking
  149. Sum of Two IntegersmediumBit Manipulation
  150. Encode and Decode StringsmediumDesignStrings

How I'd work it

  1. 1

    Finish the Blind 75 core first

    The 150 grows out of the 75. The order below puts those problems early, so the foundation comes first.

  2. 2

    Pace it by topic

    Finish a topic before you start the next. Ten problems a week for fifteen weeks beats a month of cramming.

  3. 3

    Revisit the shaky ones

    Rewrite a problem from a blank file a few days later. Then explain it out loud without notes.

Two problems a day, five days a week, finishes this list in about 15 weeks.

The list by pattern

Where Coco comes in

Coco is an AI study partner, not a person. She listens while you explain your code, asks what a line does and never hands you the fix. Sign in free to type with Coco, up to a daily limit, and to talk with her for one hour. After that, talking comes with the $79 pack. Anyone can open the editor and run their code.

Questions people ask

How long does the NeetCode 150 take?
Two problems a day, five days a week, takes about fifteen weeks. Plan the calendar before you start.
Should I do the Blind 75 or the NeetCode 150?
Start with the Blind 75 if your interview is close. Choose the 150 when you have months and want more practice per pattern.
Is this the same order NeetCode uses?
No. The membership matches the list. The order is mine, built to introduce topics gently.

Keep going

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