Problems

3,898+ problems · 938 Easy · 2039 Medium · 921 Hard

Title	Solution	Practice	Difficulty	Companies	Topics
251. Flatten 2D Vector	Solution	Solve	Medium	Airbnb+3	Array Design+2
252. Meeting Rooms	Solution	Solve	Easy	Amazon+9	Array Sorting
253. Meeting Rooms II	Solution	Solve	Medium	Adobe+42	Array Greedy+4
254. Factor Combinations	Solution	Solve	Medium	LinkedIn+1	Backtracking
255. Verify Preorder Sequence in Binary Search Tree	Solution	Solve	Medium	Expedia+4	Array Binary Search Tree+5
256. Paint House	Solution	Solve	Medium	Amazon+7	Array Dynamic Programming
257. Binary Tree Paths	Solution	Solve	Easy	Amazon+7	Backtracking Binary Tree+3
258. Add Digits	Solution	Solve	Easy	Adobe+10	Math Number Theory+1
259. 3Sum Smaller	Solution	Solve	Medium	Google+6	Array Binary Search+2
260. Single Number III	Solution	Solve	Medium	Amazon+7	Array Bit Manipulation
261. Graph Valid Tree	Solution	Solve	Medium	Amazon+7	Breadth-First Search Depth-First Search+2
262. Trips and Users	Solution	Solve	Hard	Amazon+5	Database
263. Ugly Number	Solution	Solve	Easy	Amazon+6	Math
264. Ugly Number II	Solution	Solve	Medium	Amazon+6	Dynamic Programming Hash Table+2
265. Paint House II	Solution	Solve	Hard	LinkedIn+1	Array Dynamic Programming
266. Palindrome Permutation	Solution	Solve	Easy	Apple+7	Bit Manipulation Hash Table+1
267. Palindrome Permutation II	Solution	Solve	Medium	Meta	Backtracking Hash Table+1
268. Missing Number	Solution	Solve	Easy	Adobe+20	Array Binary Search+4
269. Alien Dictionary	Solution	Solve	Hard	Airbnb+16	Array Breadth-First Search+4
270. Closest Binary Search Tree Value	Solution	Solve	Easy	Amazon+8	Binary Search Binary Search Tree+3
271. Encode and Decode Strings	Solution	Solve	Medium	Amazon+10	Array Design+1
272. Closest Binary Search Tree Value II	Solution	Solve	Hard	Amazon+2	Binary Search Tree Binary Tree+5
273. Integer to English Words	Solution	Solve	Hard	Amazon+24	Math Recursion+1
274. H-Index	Solution	Solve	Medium	Adobe+10	Array Counting Sort+1
275. H-Index II	Solution	Solve	Medium	Meta	Array Binary Search
276. Paint Fence	Solution	Solve	Medium	Google+2	Dynamic Programming
277. Find the Celebrity	Solution	Solve	Medium	Amazon+13	Graph Interactive+1
278. First Bad Version	Solution	Solve	Easy	Adobe+6	Binary Search Interactive
279. Perfect Squares	Solution	Solve	Medium	Accenture+11	Breadth-First Search Dynamic Programming+1
280. Wiggle Sort	Solution	Solve	Medium	Amazon+3	Array Greedy+1
281. Zigzag Iterator	Solution	Solve	Medium	Amazon+3	Array Design+2
282. Expression Add Operators	Solution	Solve	Hard	Amazon+6	Backtracking Math+1
283. Move Zeroes	Solution	Solve	Easy	Accenture+48	Array Two Pointers
284. Peeking Iterator	Solution	Solve	Medium	Apple+4	Array Design+1
285. Inorder Successor in BST	Solution	Solve	Medium	Amazon+5	Binary Search Tree Binary Tree+2
286. Walls and Gates	Solution	Solve	Medium	Amazon+11	Array Breadth-First Search+1
287. Find the Duplicate Number	Solution	Solve	Medium	Accenture+22	Array Binary Search+2
288. Unique Word Abbreviation	Solution	Solve	Medium	Google+1	Array Design+2
289. Game of Life	Solution	Solve	Medium	Acorns+15	Array Matrix+1
290. Word Pattern	Solution	Solve	Easy	Amazon+9	Hash Table String
291. Word Pattern II	Solution	Solve	Medium	Amazon+5	Backtracking Hash Table+1
292. Nim Game	Solution	Solve	Easy	Adobe+5	Brainteaser Game Theory+1
293. Flip Game	Solution	Solve	Easy	Google	String
294. Flip Game II	Solution	Solve	Medium	Google	Backtracking Dynamic Programming+3
295. Find Median from Data Stream	Solution	Solve	Hard	Amazon+37	Data Stream Design+3
296. Best Meeting Point	Solution	Solve	Hard	Amazon+8	Array Math+2
297. Serialize and Deserialize Binary Tree	Solution	Solve	Hard	Adobe+26	Binary Tree Breadth-First Search+4
298. Binary Tree Longest Consecutive Sequence	Solution	Solve	Medium	Amazon+3	Binary Tree Depth-First Search+1
299. Bulls and Cows	Solution	Solve	Medium	Amazon+5	Counting Hash Table+1
300. Longest Increasing Subsequence	Solution	Solve	Medium	Accenture+29	Array Binary Search+1