Solutions & Explanations

Browse 4,029+ detailed solutions with multiple approaches, code in Python, Java, C++ and more.

4,029 Solutions961 Easy2102 Medium966 Hard

Title	Difficulty	Acceptance	Topics	Solution
260. Single Number III	Medium	70.2%	Array Bit Manipulation	Read
261. Graph Valid Tree	Medium	49.9%	Breadth-First Search Depth-First Search+2	Read
264. Ugly Number II	Medium	49.7%	Dynamic Programming Hash Table+2	Read
267. Palindrome Permutation II	Medium	41.9%	Backtracking Hash Table+1	Read
271. Encode and Decode Strings	Medium	51.9%	Array Design+1	Read
274. H-Index	Medium	41.8%	Array Counting Sort+1	Read
275. H-Index II	Medium	40.0%	Array Binary Search	Read
276. Paint Fence	Medium	48.3%	Dynamic Programming	Read
277. Find the Celebrity	Medium	48.9%	Graph Interactive+1	Read
279. Perfect Squares	Medium	56.4%	Breadth-First Search Dynamic Programming+1	Read
280. Wiggle Sort	Medium	68.5%	Array Greedy+1	Read
281. Zigzag Iterator	Medium	67.1%	Array Design+2	Read
284. Peeking Iterator	Medium	61.9%	Array Design+1	Read
285. Inorder Successor in BST	Medium	51.2%	Binary Search Tree Binary Tree+2	Read
286. Walls and Gates	Medium	63.9%	Array Breadth-First Search+1	Read
287. Find the Duplicate Number	Medium	64.7%	Array Binary Search+2	Read
288. Unique Word Abbreviation	Medium	27.5%	Array Design+2	Read
289. Game of Life	Medium	73.0%	Array Matrix+1	Read
291. Word Pattern II	Medium	49.1%	Backtracking Hash Table+1	Read
294. Flip Game II	Medium	52.2%	Backtracking Dynamic Programming+3	Read
298. Binary Tree Longest Consecutive Sequence	Medium	54.7%	Binary Tree Depth-First Search+1	Read
299. Bulls and Cows	Medium	52.9%	Counting Hash Table+1	Read
300. Longest Increasing Subsequence	Medium	59.8%	Array Binary Search+1	Read
304. Range Sum Query 2D - Immutable	Medium	58.6%	Array Design+2	Read
306. Additive Number	Medium	34.2%	Backtracking String	Read
307. Range Sum Query - Mutable	Medium	43.3%	Array Binary Indexed Tree+2	Read
308. Range Sum Query 2D - Mutable	Medium	46.0%	Array Binary Indexed Tree+3	Read
309. Best Time to Buy and Sell Stock with Cooldown	Medium	62.4%	Array Dynamic Programming	Read
310. Minimum Height Trees	Medium	42.4%	Breadth-First Search Depth-First Search+2	Read
311. Sparse Matrix Multiplication	Medium	69.3%	Array Hash Table+1	Read
313. Super Ugly Number	Medium	46.6%	Array Dynamic Programming+1	Read
314. Binary Tree Vertical Order Traversal	Medium	57.8%	Binary Tree Breadth-First Search+4	Read
316. Remove Duplicate Letters	Medium	54.1%	Greedy Monotonic Stack+2	Read
318. Maximum Product of Word Lengths	Medium	61.1%	Array Bit Manipulation+1	Read
319. Bulb Switcher	Medium	56.2%	Brainteaser Math	Read
320. Generalized Abbreviation	Medium	60.4%	Backtracking Bit Manipulation+1	Read
322. Coin Change	Medium	48.7%	Array Breadth-First Search+1	Read
323. Number of Connected Components in an Undirected Graph	Medium	64.9%	Breadth-First Search Depth-First Search+2	Read
324. Wiggle Sort II	Medium	38.4%	Array Divide and Conquer+3	Read
325. Maximum Size Subarray Sum Equals k	Medium	50.8%	Array Hash Table+1	Read
328. Odd Even Linked List	Medium	62.4%	Linked List	Read
331. Verify Preorder Serialization of a Binary Tree	Medium	47.8%	Binary Tree Stack+2	Read
333. Largest BST Subtree	Medium	45.8%	Binary Search Tree Binary Tree+3	Read
334. Increasing Triplet Subsequence	Medium	39.3%	Array Greedy	Read
337. House Robber III	Medium	56.3%	Binary Tree Depth-First Search+2	Read
339. Nested List Weight Sum	Medium	85.9%	Breadth-First Search Depth-First Search	Read
340. Longest Substring with At Most K Distinct Characters	Medium	49.9%	Hash Table Sliding Window+1	Read
341. Flatten Nested List Iterator	Medium	65.6%	Depth-First Search Design+4	Read
343. Integer Break	Medium	62.6%	Dynamic Programming Math	Read
347. Top K Frequent Elements	Medium	67.3%	Array Bucket Sort+6	Read

#260Medium

Single Number III

ArrayBit Manipulation

Acceptance: 70.2%

#261Medium

Graph Valid Tree

Breadth-First SearchDepth-First SearchGraph+1

Acceptance: 49.9%

#264Medium

Ugly Number II

Dynamic ProgrammingHash TableHeap (Priority Queue)+1

Acceptance: 49.7%

#267Medium

Palindrome Permutation II

BacktrackingHash TableString

Acceptance: 41.9%

#271Medium

Encode and Decode Strings

ArrayDesignString

Acceptance: 51.9%

#274Medium

H-Index

ArrayCounting SortSorting

Acceptance: 41.8%

#275Medium

H-Index II

ArrayBinary Search

Acceptance: 40.0%

#276Medium

Paint Fence

Dynamic Programming

Acceptance: 48.3%

#277Medium

Find the Celebrity

GraphInteractiveTwo Pointers

Acceptance: 48.9%

#279Medium

Perfect Squares

Breadth-First SearchDynamic ProgrammingMath

Acceptance: 56.4%

#280Medium

Wiggle Sort

ArrayGreedySorting

Acceptance: 68.5%

#281Medium

Zigzag Iterator

ArrayDesignIterator+1

Acceptance: 67.1%

#284Medium

Peeking Iterator

ArrayDesignIterator

Acceptance: 61.9%

#285Medium

Inorder Successor in BST

Binary Search TreeBinary TreeDepth-First Search+1

Acceptance: 51.2%

#286Medium

Walls and Gates

ArrayBreadth-First SearchMatrix

Acceptance: 63.9%

#287Medium

Find the Duplicate Number

ArrayBinary SearchBit Manipulation+1

Acceptance: 64.7%

#288Medium

Unique Word Abbreviation

ArrayDesignHash Table+1

Acceptance: 27.5%

#289Medium

Game of Life

ArrayMatrixSimulation

Acceptance: 73.0%

#291Medium

Word Pattern II

BacktrackingHash TableString

Acceptance: 49.1%

#294Medium

Flip Game II

BacktrackingDynamic ProgrammingGame Theory+2

Acceptance: 52.2%

#298Medium

Binary Tree Longest Consecutive Sequence

Binary TreeDepth-First SearchTree

Acceptance: 54.7%

#299Medium

Bulls and Cows

CountingHash TableString

Acceptance: 52.9%

#300Medium

Longest Increasing Subsequence

ArrayBinary SearchDynamic Programming

Acceptance: 59.8%

#304Medium

Range Sum Query 2D - Immutable

ArrayDesignMatrix+1

Acceptance: 58.6%

#306Medium

Additive Number

BacktrackingString

Acceptance: 34.2%

#307Medium

Range Sum Query - Mutable

ArrayBinary Indexed TreeDesign+1

Acceptance: 43.3%

#308Medium

Range Sum Query 2D - Mutable

ArrayBinary Indexed TreeDesign+2

Acceptance: 46.0%

#309Medium

Best Time to Buy and Sell Stock with Cooldown

ArrayDynamic Programming

Acceptance: 62.4%

#310Medium

Minimum Height Trees

Breadth-First SearchDepth-First SearchGraph+1

Acceptance: 42.4%

#311Medium

Sparse Matrix Multiplication

ArrayHash TableMatrix

Acceptance: 69.3%

#313Medium

Super Ugly Number

ArrayDynamic ProgrammingMath

Acceptance: 46.6%

#314Medium

Binary Tree Vertical Order Traversal

Binary TreeBreadth-First SearchDepth-First Search+3

Acceptance: 57.8%

#316Medium

Remove Duplicate Letters

GreedyMonotonic StackStack+1

Acceptance: 54.1%

#318Medium

Maximum Product of Word Lengths

ArrayBit ManipulationString

Acceptance: 61.1%

#319Medium

Bulb Switcher

BrainteaserMath

Acceptance: 56.2%

#320Medium

Generalized Abbreviation

BacktrackingBit ManipulationString

Acceptance: 60.4%

#322Medium

Coin Change

ArrayBreadth-First SearchDynamic Programming

Acceptance: 48.7%

#323Medium

Number of Connected Components in an Undirected Graph

Breadth-First SearchDepth-First SearchGraph+1

Acceptance: 64.9%

#324Medium

Wiggle Sort II

ArrayDivide and ConquerGreedy+2

Acceptance: 38.4%

#325Medium

Maximum Size Subarray Sum Equals k

ArrayHash TablePrefix Sum

Acceptance: 50.8%

#328Medium

Odd Even Linked List

Linked List

Acceptance: 62.4%

#331Medium

Verify Preorder Serialization of a Binary Tree

Binary TreeStackString+1

Acceptance: 47.8%

#333Medium

Largest BST Subtree

Binary Search TreeBinary TreeDepth-First Search+2

Acceptance: 45.8%

#334Medium

Increasing Triplet Subsequence

ArrayGreedy

Acceptance: 39.3%

#337Medium

House Robber III

Binary TreeDepth-First SearchDynamic Programming+1

Acceptance: 56.3%

#339Medium

Nested List Weight Sum

Breadth-First SearchDepth-First Search

Acceptance: 85.9%

#340Medium

Longest Substring with At Most K Distinct Characters

Hash TableSliding WindowString

Acceptance: 49.9%

#341Medium

Flatten Nested List Iterator

Depth-First SearchDesignIterator+3

Acceptance: 65.6%

#343Medium

Integer Break

Dynamic ProgrammingMath

Acceptance: 62.6%

#347Medium

Top K Frequent Elements

ArrayBucket SortCounting+5

Acceptance: 67.3%

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Master DSA with Step-by-Step Solutions

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