Apple LeetCode Questions

300 questions all-time · 76 easy · 178 medium · 46 hard

#	Problem	Difficulty	Frequency	Acceptance
1	LRU Cache	Medium	100	0.5%
2	Two Sum	Easy	88	0.6%
3	Number of Islands	Medium	86	0.6%
4	Merge Intervals	Medium	85	0.5%
5	Best Time to Buy and Sell Stock	Easy	79	0.6%
6	Longest Common Prefix	Easy	79	0.5%
7	Design Hit Counter	Medium	79	0.7%
8	Rotate Array	Medium	78	0.5%
9	Valid Sudoku	Medium	77	0.6%
10	Reverse Linked List	Easy	77	0.8%
11	Group Anagrams	Medium	76	0.7%
12	Top K Frequent Elements	Medium	76	0.7%
13	Course Schedule	Medium	74	0.5%
14	Course Schedule II	Medium	74	0.6%
15	Valid Parentheses	Easy	73	0.4%
16	Longest Substring Without Repeating Characters	Medium	72	0.4%
17	Product of Array Except Self	Medium	72	0.7%
18	Rotate Image	Medium	70	0.8%
19	Valid Palindrome	Easy	70	0.5%
20	Reverse Words in a String	Medium	70	0.6%
21	Kth Largest Element in an Array	Medium	70	0.7%
22	Maximum Subarray	Medium	69	0.5%
23	Spiral Matrix	Medium	69	0.6%
24	Best Time to Buy and Sell Stock II	Medium	69	0.7%
25	Reverse Integer	Medium	68	0.3%
26	Merge k Sorted Lists	Hard	67	0.6%
27	Trapping Rain Water	Hard	66	0.7%
28	Meeting Rooms II	Medium	66	0.5%
29	Lowest Common Ancestor of a Binary Tree	Medium	65	0.7%
30	Time Based Key-Value Store	Medium	65	0.5%
31	Median of Two Sorted Arrays	Hard	63	0.5%
32	Reverse Bits	Easy	63	0.7%
33	Subarray Sum Equals K	Medium	63	0.5%
34	Subarray Product Less Than K	Medium	63	0.5%
35	Merge Two Sorted Lists	Easy	62	0.7%
36	Find First and Last Position of Element in Sorted Array	Medium	62	0.5%
37	Number of 1 Bits	Easy	62	0.8%
38	Design Circular Queue	Medium	62	0.5%
39	Snapshot Array	Medium	62	0.4%
40	Move Zeroes	Easy	61	0.6%
41	Find Median from Data Stream	Hard	61	0.5%
42	Climbing Stairs	Easy	60	0.5%
43	Word Ladder	Hard	60	0.5%
44	Min Stack	Medium	60	0.6%
45	Compare Version Numbers	Medium	60	0.5%
46	Basic Calculator II	Medium	60	0.5%
47	Search a 2D Matrix II	Medium	60	0.6%
48	Insert Delete GetRandom O(1)	Medium	60	0.6%
49	Find the Index of the First Occurrence in a String	Easy	58	0.5%
50	Merge Sorted Array	Easy	58	0.6%
51	Word Break	Medium	58	0.5%
52	Peeking Iterator	Medium	58	0.6%
53	String Compression	Medium	58	0.6%
54	3Sum	Medium	57	0.4%
55	Binary Tree Level Order Traversal	Medium	57	0.7%
56	Pascal's Triangle	Easy	57	0.8%
57	Implement Trie (Prefix Tree)	Medium	57	0.7%
58	Design Tic-Tac-Toe	Medium	57	0.6%
59	Ransom Note	Easy	57	0.7%
60	Sqrt(x)	Easy	55	0.4%
61	Max Points on a Line	Hard	55	0.3%
62	Delete Node in a Linked List	Medium	55	0.8%
63	Number of Squareful Arrays	Hard	55	0.5%
64	Number of Pairs of Strings With Concatenation Equal to Target	Medium	55	0.8%
65	Regular Expression Matching	Hard	53	0.3%
66	Remove Duplicates from Sorted Array	Easy	53	0.6%
67	Maximum Depth of Binary Tree	Easy	53	0.8%
68	Longest Consecutive Sequence	Medium	53	0.5%
69	Maximal Square	Medium	53	0.5%
70	Binary Tree Paths	Easy	53	0.7%
71	First Unique Character in a String	Easy	53	0.7%
72	Array Nesting	Medium	53	0.6%
73	Best Time to Buy and Sell Stock with Transaction Fee	Medium	53	0.7%
74	Design HashMap	Easy	53	0.7%
75	Maximum Rows Covered by Columns	Medium	53	0.6%
76	Count the Number of Incremovable Subarrays II	Hard	53	0.4%
77	Count the Number of Incremovable Subarrays I	Easy	53	0.6%
78	Find the Grid of Region Average	Medium	53	0.4%
79	Calculate Score After Performing Instructions	Medium	53	0.6%
80	Find Servers That Handled Most Number of Requests	Hard	53	0.5%
81	Remove Nth Node From End of List	Medium	51	0.5%
82	Two Sum II - Input Array Is Sorted	Medium	51	0.7%
83	Serialize and Deserialize Binary Tree	Hard	51	0.6%
84	Flatten Nested List Iterator	Medium	51	0.7%
85	Longest Palindromic Substring	Medium	48	0.4%
86	Container With Most Water	Medium	48	0.6%
87	Letter Combinations of a Phone Number	Medium	48	0.7%
88	Generate Parentheses	Medium	48	0.8%
89	Search in Rotated Sorted Array	Medium	48	0.5%
90	Implement Queue using Stacks	Easy	48	0.7%
91	Decode String	Medium	48	0.6%
92	Task Scheduler	Medium	48	0.6%
93	Find K Closest Elements	Medium	48	0.5%
94	Fibonacci Number	Easy	48	0.7%
95	Remove All Adjacent Duplicates In String	Easy	48	0.7%
96	Find Winner on a Tic Tac Toe Game	Easy	48	0.5%
97	Jump Game	Medium	46	0.4%
98	Text Justification	Hard	46	0.5%
99	Meeting Rooms	Easy	46	0.6%
100	Integer to English Words	Hard	46	0.4%
101	Reverse String	Easy	46	0.8%
102	Flood Fill	Easy	46	0.7%
103	String to Integer (atoi)	Medium	43	0.2%
104	Roman to Integer	Easy	43	0.7%
105	Permutations	Medium	43	0.8%
106	Insert Interval	Medium	43	0.5%
107	Sliding Window Maximum	Hard	43	0.5%
108	Coin Change	Medium	43	0.5%
109	Add Two Numbers	Medium	39	0.5%
110	Set Matrix Zeroes	Medium	39	0.6%
111	Word Search	Medium	39	0.5%
112	Interleaving String	Medium	39	0.4%
113	Gas Station	Medium	39	0.5%
114	Valid Anagram	Easy	39	0.7%
115	Missing Number	Easy	39	0.7%
116	Fizz Buzz	Easy	39	0.8%
117	LFU Cache	Hard	39	0.5%
118	Cheapest Flights Within K Stops	Medium	39	0.4%
119	Middle of the Linked List	Easy	39	0.8%
120	Rotting Oranges	Medium	39	0.6%
121	Lowest Common Ancestor of a Binary Tree III	Medium	39	0.8%
122	Maximum Frequency Stack	Hard	39	0.7%
123	Distribute Money to Maximum Children	Easy	39	0.2%
124	Keys and Rooms	Medium	39	0.8%
125	Path Sum	Easy	39	0.6%
126	Best Time to Buy and Sell Stock with Cooldown	Medium	39	0.6%
127	Find All Lonely Numbers in the Array	Medium	39	0.6%
128	Total Hamming Distance	Medium	39	0.5%
129	Serialize and Deserialize N-ary Tree	Hard	39	0.7%
130	Edit Distance	Medium	39	0.6%
131	Combination Sum	Medium	35	0.8%
132	Simplify Path	Medium	35	0.5%
133	Sort Colors	Medium	35	0.7%
134	Reverse Linked List II	Medium	35	0.5%
135	Best Time to Buy and Sell Stock III	Hard	35	0.5%
136	Binary Tree Maximum Path Sum	Hard	35	0.4%
137	Find Peak Element	Medium	35	0.5%
138	Best Time to Buy and Sell Stock IV	Hard	35	0.5%
139	House Robber	Medium	35	0.5%
140	Happy Number	Easy	35	0.6%
141	H-Index	Medium	35	0.4%
142	Binary Tree Vertical Order Traversal	Medium	35	0.6%
143	Odd Even Linked List	Medium	35	0.6%
144	Kth Smallest Element in a Sorted Matrix	Medium	35	0.6%
145	Find All Anagrams in a String	Medium	35	0.5%
146	Validate IP Address	Medium	35	0.3%
147	Palindromic Substrings	Medium	35	0.7%
148	Valid Palindrome II	Easy	35	0.4%
149	Capacity To Ship Packages Within D Days	Medium	35	0.7%
150	Apple Redistribution into Boxes	Easy	35	0.8%
151	Knight Probability in Chessboard	Medium	35	0.6%
152	Exam Room	Medium	35	0.4%
153	Alien Dictionary	Hard	35	0.4%
154	Design Log Storage System	Medium	35	0.6%
155	Design Add and Search Words Data Structure	Medium	35	0.5%
156	Maximum Path Quality of a Graph	Hard	35	0.6%
157	Convert Sorted Array to Binary Search Tree	Easy	35	0.8%
158	Design Memory Allocator	Medium	35	0.5%
159	Brace Expansion	Medium	35	0.7%
160	4Sum	Medium	29	0.4%
161	Remove Element	Easy	29	0.6%
162	Permutations II	Medium	29	0.6%
163	Add Binary	Easy	29	0.6%
164	Search a 2D Matrix	Medium	29	0.5%
165	Largest Rectangle in Histogram	Hard	29	0.5%
166	Validate Binary Search Tree	Medium	29	0.4%
167	Same Tree	Easy	29	0.7%
168	Reorder List	Medium	29	0.7%
169	Evaluate Reverse Polish Notation	Medium	29	0.6%
170	Find Minimum in Rotated Sorted Array	Medium	29	0.5%
171	Intersection of Two Linked Lists	Easy	29	0.6%
172	House Robber II	Medium	29	0.5%
173	Contains Duplicate	Easy	29	0.6%
174	The Skyline Problem	Hard	29	0.5%
175	Basic Calculator	Hard	29	0.5%
176	Reconstruct Itinerary	Hard	29	0.4%
177	Intersection of Two Arrays	Easy	29	0.8%
178	Island Perimeter	Easy	29	0.7%
179	Next Greater Element II	Medium	29	0.7%
180	Find Largest Value in Each Tree Row	Medium	29	0.7%
181	Continuous Subarray Sum	Medium	29	0.3%
182	Maximum Product of Three Numbers	Easy	29	0.5%
183	Top K Frequent Words	Medium	29	0.6%
184	Random Pick with Weight	Medium	29	0.5%
185	Sum of Subarray Minimums	Medium	29	0.4%
186	K Closest Points to Origin	Medium	29	0.7%
187	Determine if Two Strings Are Close	Medium	29	0.5%
188	Employee Free Time	Hard	29	0.7%
189	String Compression III	Medium	29	0.7%
190	Robot Bounded In Circle	Medium	29	0.6%
191	Best Poker Hand	Easy	29	0.6%
192	Logger Rate Limiter	Easy	29	0.8%
193	Minimum Knight Moves	Medium	29	0.4%
194	Word Ladder II	Hard	29	0.3%
195	Longest Substring with At Most K Distinct Characters	Medium	29	0.5%
196	Find Pivot Index	Easy	29	0.6%
197	Design Browser History	Medium	29	0.8%
198	Read N Characters Given read4 II - Call Multiple Times	Hard	29	0.4%
199	Binary Tree Right Side View	Medium	29	0.7%
200	Short Encoding of Words	Medium	29	0.6%
201	Sudoku Solver	Hard	29	0.7%
202	My Calendar II	Medium	29	0.6%
203	Interval List Intersections	Medium	29	0.7%
204	Shortest Path in Binary Matrix	Medium	29	0.5%
205	Convert Sorted List to Binary Search Tree	Medium	29	0.7%
206	Paths in Matrix Whose Sum Is Divisible by K	Hard	29	0.6%
207	Longest Increasing Path in a Matrix	Hard	29	0.6%
208	Find the Celebrity	Medium	29	0.5%
209	Zigzag Conversion	Medium	22	0.5%
210	Reverse Nodes in k-Group	Hard	22	0.7%
211	First Missing Positive	Hard	22	0.4%
212	Jump Game II	Medium	22	0.4%
213	Minimum Window Substring	Hard	22	0.5%
214	Subsets II	Medium	22	0.6%
215	Decode Ways	Medium	22	0.4%
216	Symmetric Tree	Easy	22	0.6%
217	Copy List with Random Pointer	Medium	22	0.6%
218	Second Highest Salary	Medium	22	0.5%
219	Remove Linked List Elements	Easy	22	0.5%
220	Count Primes	Medium	22	0.4%
221	Contains Duplicate II	Easy	22	0.5%
222	Implement Stack using Queues	Easy	22	0.7%
223	Lowest Common Ancestor of a Binary Search Tree	Medium	22	0.7%
224	First Bad Version	Easy	22	0.5%
225	Reverse Vowels of a String	Easy	22	0.6%
226	Design Twitter	Medium	22	0.4%
227	Longest Repeating Character Replacement	Medium	22	0.6%
228	Max Consecutive Ones	Easy	22	0.7%
229	Reverse Pairs	Hard	22	0.3%
230	01 Matrix	Medium	22	0.5%
231	Diameter of Binary Tree	Easy	22	0.7%
232	Can Place Flowers	Easy	22	0.3%
233	Asteroid Collision	Medium	22	0.5%
234	Similar String Groups	Hard	22	0.6%
235	Maximize Distance to Closest Person	Medium	22	0.5%
236	Transpose Matrix	Easy	22	0.8%
237	Spiral Matrix III	Medium	22	0.8%
238	Snakes and Ladders	Medium	22	0.5%
239	Verifying an Alien Dictionary	Easy	22	0.6%
240	Minimum Remove to Make Valid Parentheses	Medium	22	0.7%
241	Product of the Last K Numbers	Medium	22	0.6%
242	Dot Product of Two Sparse Vectors	Medium	22	0.9%
243	Sum of Subarray Ranges	Medium	22	0.6%
244	First Letter to Appear Twice	Easy	22	0.8%
245	Shortest Distance from All Buildings	Hard	22	0.4%
246	Web Crawler Multithreaded	Medium	22	0.5%
247	Word Pattern II	Medium	22	0.5%
248	Max Chunks To Make Sorted	Medium	22	0.6%
249	Binary Tree Zigzag Level Order Traversal	Medium	22	0.6%
250	Split Strings by Separator	Easy	22	0.8%
251	Goat Latin	Easy	22	0.7%
252	Guess the Word	Hard	22	0.4%
253	Sliding Window Median	Hard	22	0.4%
254	Image Smoother	Easy	22	0.7%
255	Clone Graph	Medium	22	0.7%
256	Walking Robot Simulation	Medium	22	0.6%
257	Intersection of Three Sorted Arrays	Easy	22	0.8%
258	Read N Characters Given Read4	Easy	22	0.4%
259	Optimize Water Distribution in a Village	Hard	22	0.7%
260	Longest Common Subsequence	Medium	22	0.6%
261	Minimize Maximum Component Cost	Medium	22	0.4%
262	Substring with Concatenation of All Words	Hard	22	0.3%
263	Binary Search Tree Iterator	Medium	22	0.8%
264	Shortest Word Distance	Easy	22	0.7%
265	Minimum Speed to Arrive on Time	Medium	22	0.5%
266	Maximum Population Year	Easy	22	0.6%
267	Counting Bits	Easy	22	0.8%
268	Sentence Similarity II	Medium	22	0.5%
269	Design Linked List	Medium	22	0.3%
270	Encode and Decode TinyURL	Medium	22	0.9%
271	Water and Jug Problem	Medium	22	0.5%
272	Minimum Size Subarray Sum	Medium	22	0.5%
273	Non-overlapping Intervals	Medium	22	0.6%
274	The Maze	Medium	22	0.6%
275	Number of Recent Calls	Easy	22	0.8%
276	Evaluate Division	Medium	22	0.6%
277	Sort an Array	Medium	22	0.6%
278	Assign Cookies	Easy	22	0.6%
279	Word Search II	Hard	22	0.4%
280	Meeting Scheduler	Medium	22	0.6%
281	Max Area of Island	Medium	22	0.7%
282	Number of Changing Keys	Easy	22	0.8%
283	One Edit Distance	Medium	22	0.3%
284	Exclusive Time of Functions	Medium	22	0.7%
285	Minimum Falling Path Sum	Medium	22	0.6%
286	Permutation in String	Medium	22	0.5%
287	Maximum Sum Circular Subarray	Medium	22	0.5%
288	Remove Duplicates from Sorted List II	Medium	22	0.5%
289	Construct Binary Tree from Preorder and Postorder Traversal	Medium	22	0.8%
290	Convert Object to JSON String	Medium	22	0.8%
291	Moving Average from Data Stream	Easy	22	0.8%
292	All Nodes Distance K in Binary Tree	Medium	22	0.7%
293	All O`one Data Structure	Hard	22	0.4%
294	Longest Happy Prefix	Hard	22	0.5%
295	Parse Lisp Expression	Hard	22	0.5%
296	Balanced Binary Tree	Easy	22	0.6%
297	Find Distance in a Binary Tree	Medium	22	0.7%
298	Valid Parenthesis String	Medium	22	0.4%
299	Design Task Manager	Medium	22	0.5%
300	Koko Eating Bananas	Medium	22	0.5%

How to read this list

The tabs at the top split the questions by how recently people said they were asked in interviews. "Last 30 Days" is the past month, "Last 3 Months" is the past quarter, and so on. "All Time" is every question on record for this company.

Frequency is a score from 0 to 100 for how often a question showed up in that time window. A higher number means it came up more often, so the list starts with the most common questions first. Acceptance is the share of submissions that pass on LeetCode. Click any question to open it on LeetCode.

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