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NeetCode 250Official

NeetCode 150 plus 100 more beginner-friendly problems. The most approachable list for people completely new to algorithms. Each topic has extra easy problems.

By FleetCode249 problems60 Easy154 Medium35 Hard25 followersUpdated 23 Mar 2026

Start: Concatenation of Array

249problems

60Easy

154Medium

35Hard

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

Showing 60 of 249 problems · Easy · Clear

TitleSolutionAcceptDifficultyTopics

1929. Concatenation of ArrayVideo

Solution90.2%Easy

Array, Simulation· 7 companies

217. Contains DuplicateVideo

Solution64.8%Easy

Array, Hash Table +1· 20 companies

242. Valid AnagramVideo

Solution68.5%Easy

Hash Table, Sorting +1· 40 companies

1. Two SumVideo

Solution57.8%Easy

Array, Hash Table· 127 companies

14. Longest Common PrefixVideo

Solution48.6%Easy

String, Trie· 60 companies

27. Remove ElementVideo

Solution62.2%Easy

Array, Two Pointers· 10 companies

169. Majority ElementVideo

Solution66.2%Easy

Array, Counting +3· 22 companies

705. Design HashSetVideo

Solution67.9%Easy

Array, Design +3· 6 companies

706. Design HashMapVideo

Solution66.5%Easy

Array, Design +3· 13 companies

344. Reverse StringVideo

Solution81.2%Easy

String, Two Pointers· 16 companies

125. Valid PalindromeVideo

Solution54.2%Easy

String, Two Pointers· 39 companies

680. Valid Palindrome IIVideo

Solution44.7%Easy

Greedy, String +1· 16 companies

1768. Merge Strings AlternatelyVideo

Solution82.1%Easy

String, Two Pointers· 11 companies

88. Merge Sorted ArrayVideo

Solution55.7%Easy

Array, Sorting +1· 37 companies

26. Remove Duplicates from Sorted ArrayVideo

Solution63.7%Easy

Array, Two Pointers· 26 companies

219. Contains Duplicate IIVideo

Solution51.6%Easy

Array, Hash Table +1· 15 companies

121. Best Time to Buy and Sell StockVideo

Solution57.1%Easy

Array, Dynamic Programming· 92 companies

682. Baseball GameVideo

Solution80.8%Easy

Array, Simulation +1· 6 companies

20. Valid ParenthesesVideo

Solution45.2%Easy

Stack, String· 113 companies

225. Implement Stack using QueuesVideo

Solution70.1%Easy

Design, Queue +1· 9 companies

232. Implement Queue using StacksVideo

Solution70.2%Easy

Design, Queue +1· 12 companies

704. Binary SearchVideo

Solution61.2%Easy

Array, Binary Search· 11 companies

35. Search Insert PositionVideo

Solution52.1%Easy

Array, Binary Search· 12 companies

374. Guess Number Higher or LowerVideo

Solution58.5%Easy

Binary Search, Interactive· 6 companies

69. Sqrt(x)Video

Solution42.2%Easy

Binary Search, Math· 17 companies

206. Reverse Linked ListVideo

Solution81.0%Easy

Linked List, Recursion· 34 companies

21. Merge Two Sorted ListsVideo

Solution68.7%Easy

Linked List, Recursion· 36 companies

141. Linked List CycleVideo

Solution55.2%Easy

Hash Table, Linked List +1· 24 companies

94. Binary Tree Inorder TraversalVideo

Solution80.4%Easy

Binary Tree, Depth-First Search +2· 7 companies

144. Binary Tree Preorder TraversalVideo

Solution76.6%Easy

Binary Tree, Depth-First Search +2· 5 companies

145. Binary Tree Postorder TraversalVideo

Solution79.0%Easy

Binary Tree, Depth-First Search +2· 5 companies

226. Invert Binary TreeVideo

Solution80.5%Easy

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

104. Maximum Depth of Binary TreeVideo

Solution78.6%Easy

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

543. Diameter of Binary TreeVideo

Solution66.4%Easy

Binary Tree, Depth-First Search +1· 20 companies

110. Balanced Binary TreeVideo

Solution59.2%Easy

Binary Tree, Depth-First Search +1· 9 companies

100. Same TreeVideo

Solution68.0%Easy

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

572. Subtree of Another TreeVideo

Solution52.0%Easy

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

703. Kth Largest Element in a StreamVideo

Solution61.4%Easy

Binary Search Tree, Binary Tree +4· 11 companies

1046. Last Stone WeightVideo

Solution66.4%Easy

Array, Heap (Priority Queue)· 13 companies

1863. Sum of All Subset XOR TotalsVideo

Solution90.1%Easy

Array, Backtracking +4· 5 companies

463. Island PerimeterVideo

Solution74.3%Easy

Array, Breadth-First Search +2· 9 companies

953. Verifying an Alien DictionaryVideo

Solution55.9%Easy

Array, Hash Table +1· 8 companies

997. Find the Town JudgeVideo

Solution51.2%Easy

Array, Graph +1· 7 companies

70. Climbing StairsVideo

Solution54.0%Easy

Dynamic Programming, Math +1· 37 companies

746. Min Cost Climbing StairsVideo

Solution68.7%Easy

Array, Dynamic Programming· 7 companies

1137. N-th Tribonacci NumberVideo

Solution63.2%Easy

Dynamic Programming, Math +1· 7 companies

860. Lemonade ChangeVideo

Solution59.6%Easy

Array, Greedy· 8 companies

252. Meeting RoomsVideoPremium

Solution59.4%Easy

Array, Sorting· 10 companies

168. Excel Sheet Column TitleVideo

Solution47.9%Easy

Math, String· 10 companies

1071. Greatest Common Divisor of StringsVideo

Solution54.1%Easy

Math, String· 7 companies

867. Transpose MatrixVideo

Solution77.4%Easy

Array, Matrix +1· 7 companies

202. Happy NumberVideo

Solution60.0%Easy

Hash Table, Math +1· 27 companies

66. Plus OneVideo

Solution50.3%Easy

Array, Math· 13 companies

13. Roman to IntegerVideo

Solution67.0%Easy

Hash Table, Math +1· 36 companies

136. Single NumberVideo

Solution78.1%Easy

Array, Bit Manipulation· 15 companies

191. Number of 1 BitsVideo

Solution77.7%Easy

Bit Manipulation, Divide and Conquer· 11 companies

338. Counting BitsVideo

Solution80.5%Easy

Bit Manipulation, Dynamic Programming· 9 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

268. Missing NumberVideo

Solution72.4%Easy

Array, Binary Search +4· 19 companies

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