Algorithms Interview

Leetcode

Leetcode

1. Two Sum done

Description: Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.
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Solution 1: Pattern Two Pointers, Time Complexity: O(nlogn),
Solution 2. Use a hashtable to store

2. Add Two Numbers

Description: Given two non-negative integers represented by linked list in reverse order. Add the two numbers and return the sum as a linked list.
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3. Longest Substring Without Repeating Characters done

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Solution: [[][]]

4. Median of Two Sorted Arrays

5. Longest Palindromic Substring

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Description:

Solution 1: Brute force, Time Complexity: O(n^3)

Solution 2: Dynamic Programming

6. Zigzag Conversion

7. Reverse Integer

8. String to Integer (atoi)

9. Palindrome Number

10. Regular Expression Matching

11. Container With Most Water

12. Integer to Roman

13. Roman to Integer

14. Longest Common Prefix

15. 3Sum

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Solution 1: Two Pointers

16. 3Sum Closest

17. Letter Combinations of a Phone Number

18. 4Sum

19. Remove Nth Node From End of List

20. Valid Parentheses

21. Merge Two Sorted Lists done

22. Generate Parentheses

23. Merge k Sorted Lists

24. Swap Nodes in Pairs

25. Reverse Nodes in k-Group

26. Remove Duplicates from Sorted Array done

27. Remove Element

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

29. Divide Two Integers

30. Substring with Concatenation of All Words

31. Next Permutation

32. Longest Valid Parentheses

33. Search in Rotated Sorted Array

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Pattern: Binary Search

34. Find First and Last Position of Element in Sorted Array done

35. Search Insert Position

36. Valid Sudoku

37. Sudoku Solver

38. Count and Say

39. Combination Sum

40. Combination Sum II

41. First Missing Positive

42. Trapping Rain Water

43. Multiply Strings

44. Wildcard Matching

45. Jump Game II

46. Permutations

47. Permutations II

48. Rotate Image

49. Group Anagrams

50. Pow(x, n)

51. N-Queens

52. N-Queens II

53. Maximum Subarray

54. Spiral Matrix

55. Jump Game

56. Merge Intervals done

57. Insert Interval

58. Length of Last Word

59. Spiral Matrix II

60. Permutation Sequence

61. Rotate List

62. Unique Paths

63. Unique Paths II

64. Minimum Path Sum

Pattern: Dynamic Programming

65. Valid Number

66. Plus One

67. Add Binary

68. Text Justification

69. Sqrt(x)

70. Climbing Stairs

71. Simplify Path

72. Edit Distance

73. Set Matrix Zeroes

74. Search a 2D Matrix

75. Sort Colors

76. Minimum Window Substring

77. Combinations

78. Subsets

79. Word Search

80. Remove Duplicates from Sorted Array II

81. Search in Rotated Sorted Array II

82. Remove Duplicates from Sorted List II

83. Remove Duplicates from Sorted List

84. Largest Rectangle in Histogram

85. Maximal Rectangle

86. Partition List

87. Scramble String

88. Merge Sorted Array

89. Gray Code

90. Subsets II

91. Decode Ways

92. Reverse Linked List II

93. Restore IP Addresses

94. Binary Tree Inorder Traversal

95. Unique Binary Search Trees II

96. Unique Binary Search Trees

97. Interleaving String

98. Validate Binary Search Tree

99. Recover Binary Search Tree

100. Same Tree

101. Symmetric Tree

102. Binary Tree Level Order Traversal

103. Binary Tree Zigzag Level Order Traversal

104. Maximum Depth of Binary Tree done

105. Construct Binary Tree from Preorder and Inorder Traversal done

106. Construct Binary Tree from Inorder and Postorder Traversal

107. Binary Tree Level Order Traversal II

108. Convert Sorted Array to Binary Search Tree

109. Convert Sorted List to Binary Search Tree

110. Balanced Binary Tree done

111. Minimum Depth of Binary Tree

112. Path Sum

113. Path Sum II

114. Flatten Binary Tree to Linked List

115. Distinct Subsequences

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116. Populating Next Right Pointers in Each Node

117. Populating Next Right Pointers in Each Node II

118. Pascal’s Triangle

119. Pascal’s Triangle II

120. Triangle

121. Best Time to Buy and Sell Stock

122. Best Time to Buy and Sell Stock II

123. Best Time to Buy and Sell Stock III

124. Binary Tree Maximum Path Sum

125. Valid Palindrome

126. Word Ladder II

127. Word Ladder

128. Longest Consecutive Sequence

129. Sum Root to Leaf Numbers

130. Surrounded Regions

131. Palindrome Partitioning

132. Palindrome Partitioning II

133. Clone Graph

134. Gas Station

135. Candy

136. Single Number done

137. Single Number II

138. Copy List with Random Pointer

139. Word Break

140. Word Break II

141. Linked List Cycle

142. Linked List Cycle II

143. Reorder List

144. Binary Tree Preorder Traversal

145. Binary Tree Postorder Traversal

146. LRU Cache

147. Insertion Sort List

148. Sort List

149. Max Points on a Line

150. Evaluate Reverse Polish Notation

151. Reverse Words in a String

152. Maximum Product Subarray

[?] 153. Find Minimum in Rotated Sorted Array

154. Find Minimum in Rotated Sorted Array II

155. Min Stack

156. Binary Tree Upside Down

157. Read N Characters Given Read4

158. Read N Characters Given read4 II - Call Multiple Times

159. Longest Substring with At Most Two Distinct Characters

160. Intersection of Two Linked Lists

161. One Edit Distance

162. Find Peak Element

163. Missing Ranges

164. Maximum Gap

165. Compare Version Numbers

166. Fraction to Recurring Decimal

167. Two Sum II - Input Array Is Sorted

168. Excel Sheet Column Title

169. Majority Element

170. Two Sum III - Data structure design

171. Excel Sheet Column Number

172. Factorial Trailing Zeroes

173. Binary Search Tree Iterator

174. Dungeon Game

175. Combine Two Tables

176. Second Highest Salary

177. Nth Highest Salary

178. Rank Scores

179. Largest Number

180. Consecutive Numbers

181. Employees Earning More Than Their Managers

182. Duplicate Emails

183. Customers Who Never Order

184. Department Highest Salary

185. Department Top Three Salaries

186. Reverse Words in a String II

187. Repeated DNA Sequences

188. Best Time to Buy and Sell Stock IV

189. Rotate Array

190. Reverse Bits

191. Number of 1 Bits

192. Word Frequency

193. Valid Phone Numbers

194. Transpose File

195. Tenth Line

196. Delete Duplicate Emails

197. Rising Temperature

198. House Robber

199. Binary Tree Right Side View

200. Number of Islands

201. Bitwise AND of Numbers Range

202. Happy Number

203. Remove Linked List Elements

204. Count Primes

205. Isomorphic Strings

206. Reverse Linked List

207. Course Schedule

208. Implement Trie (Prefix Tree)

209. Minimum Size Subarray Sum

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Solution: Sliding Window

210. Course Schedule II

211. Design Add and Search Words Data Structure

212. Word Search II

213. House Robber II

214. Shortest Palindrome

215. Kth Largest Element in an Array

216. Combination Sum III

217. Contains Duplicate

218. The Skyline Problem

219. Contains Duplicate II

220. Contains Duplicate III

221. Maximal Square

222. Count Complete Tree Nodes

223. Rectangle Area

224. Basic Calculator

225. Implement Stack using Queues

226. Invert Binary Tree

227. Basic Calculator II

228. Summary Ranges

229. Majority Element II

230. Kth Smallest Element in a BST

231. Power of Two

232. Implement Queue using Stacks done

233. Number of Digit One

234. Palindrome Linked List

235. Lowest Common Ancestor of a Binary Search Tree

236. Lowest Common Ancestor of a Binary Tree

237. Delete Node in a Linked List

238. Product of Array Except Self

239. Sliding Window Maximum

240. Search a 2D Matrix II

241. Different Ways to Add Parentheses

242. Valid Anagram

243. Shortest Word Distance

244. Shortest Word Distance II

245. Shortest Word Distance III

246. Strobogrammatic Number

247. Strobogrammatic Number II

248. Strobogrammatic Number III

249. Group Shifted Strings

250. Count Univalue Subtrees

251. Flattenr2D Vector

252. Meeting Rooms

253. Meeting Rooms II

254. Factor Combinations

255. Verify Preorder Sequence in Binary Search Tree

256. Paint House

257. Binary Tree Paths

258. Add Digits

259. 3Sum Smaller

260. Single Number III done

261. Graph Valid Tree

262. Trips and Users

263. Ugly Number

264. Ugly Number II

265. Paint House II

266. Palindrome Permutation

267. Palindrome Permutation II

268. Missing Number

269. Alien Dictionary

270. Closest Binary Search Tree Value

271. Encode and Decode Strings

272. Closest Binary Search Tree Value II

273. Integer to English Words

274. H-Index

275. H-Index II

276. Paint Fence

277. Find the Celebrity

278. First Bad Version

279. Perfect Squares

280. Wiggle Sort

281. Zigzag Iterator

282. Expression Add Operators

283. Move Zeroes

284. Peeking Iterator

285. Inorder Successor in BST

286. Walls and Gates

287. Find the Duplicate Number

288. Unique Word Abbreviation

289. Game of Life

290. Word Pattern

291. Word Pattern II

292. Nim Game

293. Flip Game

294. Flip Game II

295. Find Median from Data Stream done

296. Best Meeting Point

297. Serialize and Deserialize Binary Tree

298. Binary Tree Longest Consecutive Sequence

299. Bulls and Cows

300. Longest Increasing Subsequence

Math / Bit Operation