Apple LeetCode Questions

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

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