LeetCode Study

• Shopping Junior LeetCode Practice Repository

방식

• 1 day / 1 solve
  • 가급적 하루에 한 문제씩 풀기
  • 강제성은 없으며, 끊기더라도 최대한 꾸준히 하는 습관을 들이는 것이 목표
• 스스로의 판단하에 적정 난이도의 문제를 선정
• 자율적으로 문제를 푼 뒤 Issue의 댓글로 링크 남기기

참고

회사별 문제

LinkedIn(39)

• 1 Two Sum 23.0% Easy
• 21 Merge Two Sorted Lists 35.4% Easy
• 23 Merge k Sorted Lists 23.3% Hard
• 33 Search in Rotated Sorted Array 30.2% Hard
• 34 Search for a Range 29.1% Medium
• 46 Permutations 35.7% Medium
• 47 Permutations II 28.0% Medium
• 50 Pow(x, n) 27.9% Medium
• 53 Maximum Subarray 36.6% Medium
• 56 Merge Intervals 25.3% Hard
• 57 Insert Interval 23.8% Hard
• 65 Valid Number 12.1% Hard
• 68 Text Justification 16.1% Hard
• 76 Minimum Window Substring 21.2% Hard
• 101 Symmetric Tree 33.9% Easy
• 102 Binary Tree Level Order Traversal 32.7% Easy
• 103 Binary Tree Zigzag Level Order Traversal 28.6% Medium
• 104 Maximum Depth of Binary Tree 47.8% Easy
• 127 Word Ladder 19.6% Medium
• 149 Max Points on a Line 14.2% Hard
• 150 Evaluate Reverse Polish Notation 23.5% Medium
• 152 Maximum Product Subarray 22.1% Medium
• 156 Binary Tree Upside Down 38.3% Medium
• 170 Two Sum III – Data structure design 24.0% Easy
• 173 Binary Search Tree Iterator 34.5% Medium
• 187 Repeated DNA Sequences 25.2% Medium
• 198 House Robber 34.2% Easy
• 205 Isomorphic Strings 29.5% Easy
• 236 Lowest Common Ancestor of a Binary Tree 28.8% Medium
• 238 Product of Array Except Self 42.6% Medium
• 243 Shortest Word Distance 46.3% Easy
• 244 Shortest Word Distance II 35.3% Medium
• 245 Shortest Word Distance III 46.0% Medium
• 254 Factor Combinations 34.7% Medium
• 256 Paint House 42.6% Medium
• 277 Find the Celebrity 35.1% Medium
• 297 Serialize and Deserialize Binary Tree 27.8% Hard
• 311 Sparse Matrix Multiplication 47.2% Medium
• 339 Nested List Weight Sum 54.7% Easy*

Google(90)

• Median of Two Sorted Arrays 18.6% Hard
• 10 Regular Expression Matching 22.0% Hard
• 17 Letter Combinations of a Phone Number 28.6% Medium
• 20 Valid Parentheses 29.3% Easy
• 22 Generate Parentheses 36.9% Medium
• 23 Merge k Sorted Lists 23.3% Hard
• 31 Next Permutation 26.5% Medium
• 42 Trapping Rain Water 32.2% Hard
• 44 Wildcard Matching 17.4% Hard
• 50 Pow(x, n) 27.9% Medium
• 54 Spiral Matrix 22.5% Medium
• 56 Merge Intervals 25.3% Hard
• 57 Insert Interval 23.8% Hard
• 66 Plus One 33.5% Easy
• 128 Longest Consecutive Sequence 32.1% Hard
• 133 Clone Graph 24.9% Medium
• 139 Word Break 25.2% Medium
• 140 Word Break II 19.7% Hard
• 146 LRU Cache 15.8% Hard
• 155 Min Stack 22.0% Easy
• 158 Read N Characters Given Read4 II – Call multiple times 23.4% Hard
• 159 Longest Substring with At Most Two Distinct Characters 34.7% Hard
• 162 Find Peak Element 33.0% Medium
• 163 Missing Ranges 29.2% Medium
• 166 Fraction to Recurring Decimal 15.1% Medium
• 173 Binary Search Tree Iterator 34.5% Medium
• 200 Number of Islands 27.6% Medium
• 208 Implement Trie (Prefix Tree) 25.3% Medium
• 212 Word Search II 19.3% Hard
• 214 Shortest Palindrome 19.7% Hard
• 218 The Skyline Problem 22.0% Hard
• 224 Basic Calculator 22.1% Hard
• 228 Summary Ranges 24.1% Medium
• 230 Kth Smallest Element in a BST 37.6% Medium
• 231 Power of Two 36.4% Easy
• 239 Sliding Window Maximum 27.3% Hard
• 240 Search a 2D Matrix II 34.4% Medium
• 246 Strobogrammatic Number 36.3% Easy
• 247 Strobogrammatic Number II 34.1% Medium
• 249 Group Shifted Strings 31.3% Easy
• 251 Flatten 2D Vector 33.8% Medium
• 253 Meeting Rooms II 34.6% Medium
• 257 Binary Tree Paths 28.4% Easy
• 259 3Sum Smaller 38.2% Medium
• 261 Graph Valid Tree 32.5% Medium
• 266 Palindrome Permutation 50.4% Easy
• 269 Alien Dictionary 22.9% Hard
• 270 Closest Binary Search Tree Value 34.3% Easy
• 271 Encode and Decode Strings 27.1% Medium
• 272 Closest Binary Search Tree Value II 33.1% Hard
• 274 H-Index 29.3% Medium
• 276 Paint Fence 30.9% Easy
• 279 Perfect Squares 32.5% Medium
• 280 Wiggle Sort 49.5% Medium
• 281 Zigzag Iterator 42.8% Medium
• 282 Expression Add Operators 24.8% Hard
• 284 Peeking Iterator 33.5% Medium
• 286 Walls and Gates 37.2% Medium
• 288 Unique Word Abbreviation 15.7% Easy
• 289 Game of Life 34.2% Medium
• 293 Flip Game 49.5% Easy
• 294 Flip Game II 41.3% Medium
• 295 Find Median from Data Stream 22.0% Hard
• 297 Serialize and Deserialize Binary Tree 27.8% Hard
• 298 Binary Tree Longest Consecutive Sequence 36.9% Medium
• 302 Smallest Rectangle Enclosing Black Pixels 39.0% Hard
• 305 Number of Islands II 34.0% Hard
• 308 Range Sum Query 2D – Mutable 21.6% Hard
• 309 Best Time to Buy and Sell Stock with Cooldown 36.6% Medium
• 310 Minimum Height Trees 26.6% Medium
• 312 Burst Balloons 36.4% Hard
• 313 Super Ugly Number 33.9% Medium
• 314 Binary Tree Vertical Order Traversal 30.3% Medium
• 315 Count of Smaller Numbers After Self 30.1% Hard
• 316 Remove Duplicate Letters 24.9% Hard
• 317 Shortest Distance from All Buildings 31.1% Hard
• 318 Maximum Product of Word Lengths 39.6% Medium
• 320 Generalized Abbreviation 40.8% Medium
• 321 Create Maximum Number 20.8% Hard
• 323 Number of Connected Components in an Undirected Graph 42.8% Medium
• 324 Wiggle Sort II 22.1% Medium
• 326 Power of Three 36.5% Easy
• 327 Count of Range Sum 25.9% Hard
• 329 Longest Increasing Path in a Matrix 31.2% Hard
• 330 Patching Array 28.9% Medium
• 331 Verify Preorder Serialization of a Binary Tree 31.7% Medium
• 332 Reconstruct Itinerary 23.8% Medium
• 336 Palindrome Pairs 19.5% Hard
• 340 Longest Substring with At Most K Distinct Characters 37.2% Hard
• 341 Flatten Nested List Iterator 19.8% Medium*

Uber(42)

• Two Sum 23.0% Easy
• 8 String to Integer (atoi) 13.5% Easy
• 10 Regular Expression Matching 22.0% Hard
• 13 Roman to Integer 39.2% Easy
• 17 Letter Combinations of a Phone Number 28.6% Medium
• 22 Generate Parentheses 36.9% Medium
• 23 Merge k Sorted Lists 23.3% Hard
• 24 Swap Nodes in Pairs 35.1% Easy
• 33 Search in Rotated Sorted Array 30.2% Hard
• 36 Valid Sudoku 30.5% Easy
• 37 Sudoku Solver 24.8% Hard
• 39 Combination Sum 30.9% Medium
• 49 Group Anagrams 27.4% Medium
• 54 Spiral Matrix 22.5% Medium
• 76 Minimum Window Substring 21.2% Hard
• 78 Subsets 31.3% Medium
• 91 Decode Ways 17.5% Medium
• 104 Maximum Depth of Binary Tree 47.8% Easy
• 121 Best Time to Buy and Sell Stock 36.0% Easy
• 125 Valid Palindrome 23.8% Easy
• 133 Clone Graph 24.9% Medium
• 138 Copy List with Random Pointer 26.1% Hard
• 139 Word Break 25.2% Medium
• 140 Word Break II 19.7% Hard
• 146 LRU Cache 15.8% Hard
• 155 Min Stack 22.0% Easy
• 161 One Edit Distance 28.4% Medium
• 171 Excel Sheet Column Number 41.5% Easy
• 186 Reverse Words in a String II 29.1% Medium
• 202 Happy Number 36.5% Easy
• 206 Reverse Linked List 39.4% Easy
• 208 Implement Trie (Prefix Tree) 25.3% Medium
• 230 Kth Smallest Element in a BST 37.6% Medium
• 242 Valid Anagram 41.7% Easy
• 249 Group Shifted Strings 31.3% Easy
• 254 Factor Combinations 34.7% Medium
• 262 Trips and Users 16.1% Hard
• 266 Palindrome Permutation 50.4% Easy
• 290 Word Pattern 29.0% Easy
• 291 Word Pattern II 34.8% Hard
• 297 Serialize and Deserialize Binary Tree 27.8% Har
• 337 House Robber III 37.0% Medium*

Airbnb(20)

• 1 Two Sum 23.0% Easy
• 2 Add Two Numbers 23.0% Medium
• 10 Regular Expression Matching 22.0% Hard
• 20 Valid Parentheses 29.3% Easy
• 23 Merge k Sorted Lists 23.3% Hard
• 68 Text Justification 16.1% Hard
• 108 Convert Sorted Array to Binary Search Tree 37.2% Medium
• 136 Single Number 49.6% Medium
• 160 Intersection of Two Linked Lists 30.2% Easy
• 190 Reverse Bits 29.3% Easy
• 198 House Robber 34.2% Easy
• 202 Happy Number 36.5% Easy
• 212 Word Search II 19.3% Hard
• 217 Contains Duplicate 41.1% Easy
• 219 Contains Duplicate II 29.9% Easy
• 220 Contains Duplicate III 18.5% Medium
• 221 Maximal Square 23.5% Medium
• 251 Flatten 2D Vector 33.8% Medium
• 269 Alien Dictionary 22.9% Hard
• 336 Palindrome Pairs 19.5% Hard*

Facebook(79)

• Two Sum 23.0% Easy
• 10 Regular Expression Matching 22.0% Hard
• 13 Roman to Integer 39.2% Easy
• 15 3Sum 18.8% Medium
• 17 Letter Combinations of a Phone Number 28.6% Medium
• 20 Valid Parentheses 29.3% Easy
• 23 Merge k Sorted Lists 23.3% Hard
• 25 Reverse Nodes in k-Group 27.5% Hard
• 26 Remove Duplicates from Sorted Array 33.4% Easy
• 28 Implement strStr() 24.8% Easy
• 33 Search in Rotated Sorted Array 30.2% Hard
• 38 Count and Say 28.9% Easy
• 43 Multiply Strings 23.4% Medium
• 44 Wildcard Matching 17.4% Hard
• 49 Group Anagrams 27.4% Medium
• 50 Pow(x, n) 27.9% Medium
• 56 Merge Intervals 25.3% Hard
• 57 Insert Interval 23.8% Hard
• 67 Add Binary 27.4% Easy
• 69 Sqrt(x) 25.2% Medium
• 71 Simplify Path 21.9% Medium
• 75 Sort Colors 34.7% Medium
• 76 Minimum Window Substring 21.2% Hard
• 78 Subsets 31.3% Medium
• 79 Word Search 22.9% Medium
• 80 Remove Duplicates from Sorted Array II 32.7% Medium
• 85 Maximal Rectangle 23.4% Hard
• 88 Merge Sorted Array 30.0% Easy
• 90 Subsets II 30.5% Medium
• 91 Decode Ways 17.5% Medium
• 98 Validate Binary Search Tree 20.9% Medium
• 102 Binary Tree Level Order Traversal 32.7% Easy
• 117 Populating Next Right Pointers in Each Node II 32.8% Hard
• 121 Best Time to Buy and Sell Stock 36.0% Easy
• 125 Valid Palindrome 23.8% Easy
• 127 Word Ladder 19.6% Medium
• 128 Longest Consecutive Sequence 32.1% Hard
• 133 Clone Graph 24.9% Medium
• 139 Word Break 25.2% Medium
• 146 LRU Cache 15.8% Hard
• 157 Read N Characters Given Read4 29.5% Easy
• 158 Read N Characters Given Read4 II – Call multiple times 23.4% Hard
• 161 One Edit Distance 28.4% Medium
• 168 Excel Sheet Column Title 21.6% Easy
• 173 Binary Search Tree Iterator 34.5% Medium
• 200 Number of Islands 27.6% Medium
• 206 Reverse Linked List 39.4% Easy
• 208 Implement Trie (Prefix Tree) 25.3% Medium
• 209 Minimum Size Subarray Sum 26.8% Medium
• 210 Course Schedule II 21.0% Medium
• 211 Add and Search Word – Data structure design 20.2% Medium
• 215 Kth Largest Element in an Array 33.1% Medium
• 218 The Skyline Problem 22.0% Hard
• 221 Maximal Square 23.5% Medium
• 234 Palindrome Linked List 28.0% Easy
• 235 Lowest Common Ancestor of a Binary Search Tree 37.7% Easy
• 236 Lowest Common Ancestor of a Binary Tree 28.8% Medium
• 238 Product of Array Except Self 42.6% Medium
• 252 Meeting Rooms 41.6% Easy
• 253 Meeting Rooms II 34.6% Medium
• 257 Binary Tree Paths 28.4% Easy
• 261 Graph Valid Tree 32.5% Medium
• 265 Paint House II 35.6% Hard
• 269 Alien Dictionary 22.9% Hard
• 273 Integer to English Words 18.7% Hard
• 274 H-Index 29.3% Medium
• 275 H-Index II 32.5% Medium
• 277 Find the Celebrity 35.1% Medium
• 278 First Bad Version 22.4% Easy
• 282 Expression Add Operators 24.8% Hard
• 283 Move Zeroes 44.0% Easy
• 285 Inorder Successor in BST 35.6% Medium
• 286 Walls and Gates 37.2% Medium
• 297 Serialize and Deserialize Binary Tree 27.8% Hard
• 301 Remove Invalid Parentheses 31.9% Hard
• 311 Sparse Matrix Multiplication 47.2% Medium
• 314 Binary Tree Vertical Order Traversal 30.3% Medium
• 325 Maximum Size Subarray Sum Equals k 39.9% Easy
• 334 Increasing Triplet Subsequence 33.2% Medium*

Twitter(21)

• Regular Expression Matching 22.0% Hard
• 12 Integer to Roman 38.8% Medium
• 20 Valid Parentheses 29.3% Easy
• 23 Merge k Sorted Lists 23.3% Hard
• 42 Trapping Rain Water 32.2% Hard
• 43 Multiply Strings 23.4% Medium
• 56 Merge Intervals 25.3% Hard
• 60 Permutation Sequence 25.1% Medium
• 118 Pascal’s Triangle 33.3% Easy
• 140 Word Break II 19.7% Hard
• 146 LRU Cache 15.8% Hard
• 149 Max Points on a Line 14.2% Hard
• 161 One Edit Distance 28.4% Medium
• 202 Happy Number 36.5% Easy
• 206 Reverse Linked List 39.4% Easy
• 208 Implement Trie (Prefix Tree) 25.3% Medium
• 218 The Skyline Problem 22.0% Hard
• 235 Lowest Common Ancestor of a Binary Search Tree 37.7% Easy
• 251 Flatten 2D Vector 33.8% Medium
• 269 Alien Dictionary 22.9% Hard
• 296 Best Meeting Point 46.7% Hard*

Zenefit(21)

• 4 Median of Two Sorted Arrays 18.6% Hard
• 20 Valid Parentheses 29.3% Easy
• 22 Generate Parentheses 36.9% Medium
• 42 Trapping Rain Water 32.2% Hard
• 52 N-Queens II 39.2% Hard
• 109 Convert Sorted List to Binary Search Tree 30.4% Medium
• 125 Valid Palindrome 23.8% Easy
• 146 LRU Cache 15.8% Hard
• 155 Min Stack 22.0% Easy
• 168 Excel Sheet Column Title 21.6% Easy
• 169 Majority Element 41.1% Easy
• 200 Number of Islands 27.6% Medium
• 206 Reverse Linked List 39.4% Easy
• 207 Course Schedule 26.8% Medium
• 210 Course Schedule II 21.0% Medium
• 229 Majority Element II 25.6% Medium
• 239 Sliding Window Maximum 27.3% Hard
• 251 Flatten 2D Vector 33.8% Medium
• 255 Verify Preorder Sequence in Binary Search Tree 37.1% Medium
• 261 Graph Valid Tree 32.5% Medium
• 317 Shortest Distance from All Buildings 31.1% Hard

Amazon(41)

• 1 Two Sum 23.0% Easy
• 2 Add Two Numbers 23.0% Medium
• 3 Longest Substring Without Repeating Characters 21.9% Medium
• 5 Longest Palindromic Substring 23.0% Medium
• 8 String to Integer (atoi) 13.5% Easy
• 15 3Sum 18.8% Medium
• 17 Letter Combinations of a Phone Number 28.6% Medium
• 20 Valid Parentheses 29.3% Easy
• 21 Merge Two Sorted Lists 35.4% Easy
• 23 Merge k Sorted Lists 23.3% Hard
• 42 Trapping Rain Water 32.2% Hard
• 48 Rotate Image 34.6% Medium
• 49 Group Anagrams 27.4% Medium
• 78 Subsets 31.3% Medium
• 89 Gray Code 36.3% Medium
• 98 Validate Binary Search Tree 20.9% Medium
• 102 Binary Tree Level Order Traversal 32.7% Easy
• 121 Best Time to Buy and Sell Stock 36.0% Easy
• 126 Word Ladder II 13.6% Hard
• 127 Word Ladder 19.6% Medium
• 138 Copy List with Random Pointer 26.1% Hard
• 139 Word Break 25.2% Medium
• 141 Linked List Cycle 37.0% Medium
• 146 LRU Cache 15.8% Hard
• 155 Min Stack 22.0% Easy
• 160 Intersection of Two Linked Lists 30.2% Easy
• 167 Two Sum II – Input array is sorted 47.8% Medium
• 186 Reverse Words in a String II 29.1% Medium
• 199 Binary Tree Right Side View 34.3% Medium
• 200 Number of Islands 27.6% Medium
• 204 Count Primes 24.2% Easy
• 206 Reverse Linked List 39.4% Easy
• 215 Kth Largest Element in an Array 33.1% Medium
• 234 Palindrome Linked List 28.0% Easy
• 235 Lowest Common Ancestor of a Binary Search Tree 37.7% Easy
• 236 Lowest Common Ancestor of a Binary Tree 28.8% Medium
• 238 Product of Array Except Self 42.6% Medium
• 239 Sliding Window Maximum 27.3% Hard
• 240 Search a 2D Matrix II 34.4% Medium
• 242 Valid Anagram 41.7% Easy
• 297 Serialize and Deserialize Binary Tree 27.8% Hard

Microsoft(77)

• 1 Two Sum 23.0% Easy
• 2 Add Two Numbers 23.0% Medium
• 4 Median of Two Sorted Arrays 18.6% Hard
• 5 Longest Palindromic Substring 23.0% Medium
• 8 String to Integer (atoi) 13.5% Easy
• 13 Roman to Integer 39.2% Easy
• 15 3Sum 18.8% Medium
• 20 Valid Parentheses 29.3% Easy
• 21 Merge Two Sorted Lists 35.4% Easy
• 23 Merge k Sorted Lists 23.3% Hard
• 24 Swap Nodes in Pairs 35.1% Easy
• 25 Reverse Nodes in k-Group 27.5% Hard
• 26 Remove Duplicates from Sorted Array 33.4% Easy
• 28 Implement strStr() 24.8% Easy
• 33 Search in Rotated Sorted Array 30.2% Hard
• 46 Permutations 35.7% Medium
• 47 Permutations II 28.0% Medium
• 48 Rotate Image 34.6% Medium
• 53 Maximum Subarray 36.6% Medium
• 54 Spiral Matrix 22.5% Medium
• 55 Jump Game 28.2% Medium
• 56 Merge Intervals 25.3% Hard
• 71 Simplify Path 21.9% Medium
• 73 Set Matrix Zeroes 33.4% Medium
• 75 Sort Colors 34.7% Medium
• 79 Word Search 22.9% Medium
• 88 Merge Sorted Array 30.0% Easy
• 91 Decode Ways 17.5% Medium
• 94 Binary Tree Inorder Traversal 39.6% Medium
• 98 Validate Binary Search Tree 20.9% Medium
• 101 Symmetric Tree 33.9% Easy
• 102 Binary Tree Level Order Traversal 32.7% Easy
• 103 Binary Tree Zigzag Level Order Traversal 28.6% Medium
• 106 Construct Binary Tree from Inorder and Postorder Traversal 29.0% Medium
• 112 Path Sum 31.3% Easy
• 114 Flatten Binary Tree to Linked List 31.0% Medium
• 116 Populating Next Right Pointers in Each Node 36.5% Medium
• 117 Populating Next Right Pointers in Each Node II 32.8% Hard
• 121 Best Time to Buy and Sell Stock 36.0% Easy
• 124 Binary Tree Maximum Path Sum 23.3% Hard
• 125 Valid Palindrome 23.8% Easy
• 138 Copy List with Random Pointer 26.1% Hard
• 141 Linked List Cycle 37.0% Medium
• 146 LRU Cache 15.8% Hard
• 151 Reverse Words in a String 15.7% Medium
• 153 Find Minimum in Rotated Sorted Array 36.1% Medium
• 160 Intersection of Two Linked Lists 30.2% Easy
• 162 Find Peak Element 33.0% Medium
• 165 Compare Version Numbers 17.4% Easy
• 168 Excel Sheet Column Title 21.6% Easy
• 171 Excel Sheet Column Number 41.5% Easy
• 173 Binary Search Tree Iterator 34.5% Medium
• 174 Dungeon Game 20.8% Hard
• 186 Reverse Words in a String II 29.1% Medium
• 189 Rotate Array 21.1% Easy
• 191 Number of 1 Bits 37.5% Easy
• 200 Number of Islands 27.6% Medium
• 204 Count Primes 24.2% Easy
• 206 Reverse Linked List 39.4% Easy
• 208 Implement Trie (Prefix Tree) 25.3% Medium
• 212 Word Search II 19.3% Hard
• 213 House Robber II 30.5% Medium
• 215 Kth Largest Element in an Array 33.1% Medium
• 218 The Skyline Problem 22.0% Hard
• 232 Implement Queue using Stacks 33.9% Easy
• 235 Lowest Common Ancestor of a Binary Search Tree 37.7% Easy
• 236 Lowest Common Ancestor of a Binary Tree 28.8% Medium
• 237 Delete Node in a Linked List 43.7% Easy
• 238 Product of Array Except Self 42.6% Medium
• 258 Add Digits 48.4% Easy
• 268 Missing Number 40.0% Medium
• 270 Closest Binary Search Tree Value 34.3% Easy
• 273 Integer to English Words 18.7% Hard
• 285 Inorder Successor in BST 35.6% Medium
• 297 Serialize and Deserialize Binary Tree 27.8% Hard
• 300 Longest Increasing Subsequence 34.2% Medium
• 333 Largest BST Subtree 26.5% Medium*

Snapchat(15)

• 36 Valid Sudoku 30.5% Easy
• 39 Combination Sum 30.9% Medium
• 44 Wildcard Matching 17.4% Hard
• 96 Unique Binary Search Trees 37.4% Medium
• 127 Word Ladder 19.6% Medium
• 140 Word Break II 19.7% Hard
• 146 LRU Cache 15.8% Hard
• 151 Reverse Words in a String 15.7% Medium
• 155 Min Stack 22.0% Easy
• 161 One Edit Distance 28.4% Medium
• 206 Reverse Linked List 39.4% Easy
• 269 Alien Dictionary 22.9% Hard
• 270 Closest Binary Search Tree Value 34.3% Easy
• 289 Game of Life 34.2% Medium
• 314 Binary Tree Vertical Order Traversal 30.3% Medium*

Apple(28)

• 1 Two Sum 23.0% Easy
• 4 Median of Two Sorted Arrays 18.6% Hard
• 7 Reverse Integer 23.6% Easy
• 21 Merge Two Sorted Lists 35.4% Easy
• 28 Implement strStr() 24.8% Easy
• 36 Valid Sudoku 30.5% Easy
• 42 Trapping Rain Water 32.2% Hard
• 48 Rotate Image 34.6% Medium
• 69 Sqrt(x) 25.2% Medium
• 70 Climbing Stairs 36.7% Easy
• 102 Binary Tree Level Order Traversal 32.7% Easy
• 104 Maximum Depth of Binary Tree 47.8% Easy
• 118 Pascal’s Triangle 33.3% Easy
• 149 Max Points on a Line 14.2% Hard
• 151 Reverse Words in a String 15.7% Medium
• 165 Compare Version Numbers 17.4% Easy
• 190 Reverse Bits 29.3% Easy
• 191 Number of 1 Bits 37.5% Easy
• 206 Reverse Linked List 39.4% Easy
• 207 Course Schedule 26.8% Medium
• 215 Kth Largest Element in an Array 33.1% Medium
• 221 Maximal Square 23.5% Medium
• 236 Lowest Common Ancestor of a Binary Tree 28.8% Medium
• 237 Delete Node in a Linked List 43.7% Easy
• 238 Product of Array Except Self 42.6% Medium
• 240 Search a 2D Matrix II 34.4% Medium
• 257 Binary Tree Paths 28.4% Easy
• 284 Peeking Iterator 33.5% Medium*

Yahoo(11)

• 1 Two Sum 23.0% Easy
• 4 Median of Two Sorted Arrays 18.6% Hard
• 13 Roman to Integer 39.2% Easy
• 104 Maximum Depth of Binary Tree 47.8% Easy
• 139 Word Break 25.2% Medium
• 141 Linked List Cycle 37.0% Medium
• 146 LRU Cache 15.8% Hard
• 206 Reverse Linked List 39.4% Easy
• 217 Contains Duplicate 41.1% Easy
• 284 Peeking Iterator 33.5% Medium
• 297 Serialize and Deserialize Binary Tree 27.8% Hard*

Dropbox(7)

• 1 Two Sum 23.0% Easy
• 4 Median of Two Sorted Arrays 18.6% Hard
• 17 Letter Combinations of a Phone Number 28.6% Medium
• 140 Word Break II 19.7% Hard
• 289 Game of Life 34.2% Medium
• 290 Word Pattern 29.0% Easy
• 291 Word Pattern II 34.8% Hard*

Bloomberg(57)

• 1 Two Sum 23.0% Easy
• 2 Add Two Numbers 23.0% Medium
• 3 Longest Substring Without Repeating Characters 21.9% Medium
• 5 Longest Palindromic Substring 23.0% Medium
• 7 Reverse Integer 23.6% Easy
• 8 String to Integer (atoi) 13.5% Easy
• 11 Container With Most Water 34.5% Medium
• 13 Roman to Integer 39.2% Easy
• 15 3Sum 18.8% Medium
• 16 3Sum Closest 29.0% Medium
• 20 Valid Parentheses 29.3% Easy
• 24 Swap Nodes in Pairs 35.1% Easy
• 26 Remove Duplicates from Sorted Array 33.4% Easy
• 33 Search in Rotated Sorted Array 30.2% Hard
• 42 Trapping Rain Water 32.2% Hard
• 49 Group Anagrams 27.4% Medium
• 50 Pow(x, n) 27.9% Medium
• 53 Maximum Subarray 36.6% Medium
• 56 Merge Intervals 25.3% Hard
• 62 Unique Paths 36.2% Medium
• 63 Unique Paths II 29.3% Medium
• 69 Sqrt(x) 25.2% Medium
• 79 Word Search 22.9% Medium
• 88 Merge Sorted Array 30.0% Easy
• 98 Validate Binary Search Tree 20.9% Medium
• 100 Same Tree 43.2% Easy
• 101 Symmetric Tree 33.9% Easy
• 102 Binary Tree Level Order Traversal 32.7% Easy
• 103 Binary Tree Zigzag Level Order Traversal 28.6% Medium
• 105 Construct Binary Tree from Preorder and Inorder Traversal 28.6% Medium
• 110 Balanced Binary Tree 34.0% Easy
• 113 Path Sum II 28.2% Medium
• 117 Populating Next Right Pointers in Each Node II 32.8% Hard
• 121 Best Time to Buy and Sell Stock 36.0% Easy
• 122 Best Time to Buy and Sell Stock II 42.2% Medium
• 131 Palindrome Partitioning 27.6% Medium
• 138 Copy List with Random Pointer 26.1% Hard
• 139 Word Break 25.2% Medium
• 141 Linked List Cycle 37.0% Medium
• 146 LRU Cache 15.8% Hard
• 151 Reverse Words in a String 15.7% Medium
• 155 Min Stack 22.0% Easy
• 158 Read N Characters Given Read4 II – Call multiple times 23.4% Hard
• 160 Intersection of Two Linked Lists 30.2% Easy
• 172 Factorial Trailing Zeroes 32.7% Easy
• 189 Rotate Array 21.1% Easy
• 206 Reverse Linked List 39.4% Easy
• 208 Implement Trie (Prefix Tree) 25.3% Medium
• 215 Kth Largest Element in an Array 33.1% Medium
• 225 Implement Stack using Queues 30.5% Easy
• 230 Kth Smallest Element in a BST 37.6% Medium
• 232 Implement Queue using Stacks 33.9% Easy
• 268 Missing Number 40.0% Medium
• 274 H-Index 29.3% Medium
• 283 Move Zeroes 44.0% Easy
• 287 Find the Duplicate Number 38.5% Hard
• 297 Serialize and Deserialize Binary Tree 27.8% Hard*

Yelp(12)

• 1 Two Sum 23.0% Easy
• 3 Longest Substring Without Repeating Characters 21.9% Medium
• 14 Longest Common Prefix 28.1% Easy
• 49 Group Anagrams 27.4% Medium
• 56 Merge Intervals 25.3% Hard
• 126 Word Ladder II 13.6% Hard
• 127 Word Ladder 19.6% Medium
• 151 Reverse Words in a String 15.7% Medium
• 206 Reverse Linked List 39.4% Easy
• 207 Course Schedule 26.8% Medium
• 218 The Skyline Problem 22.0% Hard
• 242 Valid Anagram 41.7% Easy*

Palantir(7)

• 136 Single Number 49.6% Medium
• 146 LRU Cache 15.8% Hard
• 217 Contains Duplicate 41.1% Easy
• 219 Contains Duplicate II 29.9% Easy
• 220 Contains Duplicate III 18.5% Medium
• 303 Range Sum Query – Immutable 24.4% Easy
• 325 Maximum Size Subarray Sum Equals k 39.9% Easy*

Adobe(12)

• 1 Two Sum 23.0% Easy
• 2 Add Two Numbers 23.0% Medium
• 3 Longest Substring Without Repeating Characters 21.9% Medium
• 4 Median of Two Sorted Arrays 18.6% Hard
• 15 3Sum 18.8% Medium
• 70 Climbing Stairs 36.7% Easy
• 169 Majority Element 41.1% Easy
• 195 Tenth Line 32.4% Easy
• 206 Reverse Linked List 39.4% Easy
• 237 Delete Node in a Linked List 43.7% Easy
• 258 Add Digits 48.4% Easy
• 292 Nim Game 52.7% Easy

How could we spread out idea in real situation?