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Apple DSA Interview Questions

303 curated coding interview questions directly asked in Apple technical rounds, sorted by frequency with recency and difficulty diagnostics.

⚡ Open Interactive Tracker (303 Problems) 🔥 Must-Solve Problem Pool 🏢 All Companies Directory

303 Total Questions

77 (25%) Easy Problems

181 (60%) Medium Problems

45 (15%) Hard Problems

🔥 Most Tested Topics:

Core DSA (88)Arrays (82)Strings (52)Trees (34)Design (19)

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Showing top 200 of 303 questions. View all 303 in the interactive tracker.

Showing 200 of 200 displayed

ID	Problem	Difficulty	Topic	Pattern	Acceptance	Frequency	Recency
146	LRU Cache	Medium	Design	Data Structure Design	47.4%	100.0%	30d
362	Design Hit Counter	Medium	Design	Data Structure Design	69.7%	100.0%	30d
560	Subarray Sum Equals K	Medium	Arrays	Sorting / Prefix / Scan	47.3%	87.5%	30d
121	Best Time to Buy and Sell Stock	Easy	Core DSA	Implementation / Reasoning	56.8%	87.5%	30d
14	Longest Common Prefix	Easy	Core DSA	Implementation / Reasoning	47.6%	87.5%	30d
477	Total Hamming Distance	Medium	Core DSA	Implementation / Reasoning	54.9%	87.5%	30d
206	Reverse Linked List	Easy	Linked List	Two Pointers	80.6%	87.5%	3m
56	Merge Intervals	Medium	Arrays	Sorting / Prefix / Scan	51.8%	75.0%	30d
210	Course Schedule II	Medium	Graphs	BFS / DFS / Topological Sort	55.5%	75.0%	30d
889	Construct Binary Tree from Preorder and Postorder Traversal	Medium	Trees	DFS / BFS	78.0%	75.0%	30d
713	Subarray Product Less Than K	Medium	Arrays	Sorting / Prefix / Scan	54.3%	75.0%	30d
2633	Convert Object to JSON String	Medium	Strings	Hashing / Sliding Window	78.1%	75.0%	30d
49	Group Anagrams	Medium	Strings	Hashing / Sliding Window	72.6%	75.0%	30d
122	Best Time to Buy and Sell Stock II	Medium	Core DSA	Implementation / Reasoning	71.1%	75.0%	30d
200	Number of Islands	Medium	Graphs	BFS / DFS / Topological Sort	64.4%	75.0%	3m
34	Find First and Last Position of Element in Sorted Array	Medium	Arrays	Sorting / Prefix / Scan	48.9%	75.0%	3m
227	Basic Calculator II	Medium	Stack / Queue	Monotonic Stack / Simulation	46.9%	75.0%	3m
380	Insert Delete GetRandom O(1)	Medium	Core DSA	Implementation / Reasoning	55.4%	75.0%	3m
428	Serialize and Deserialize N-ary Tree	Hard	Trees; Design	DFS / BFS; Data Structure Design	68.8%	75.0%	3m
54	Spiral Matrix	Medium	Arrays	Sorting / Prefix / Scan	56.8%	75.0%	3m
20	Valid Parentheses	Easy	Strings	Hashing / Sliding Window	44.2%	75.0%	all
7	Reverse Integer	Medium	Core DSA	Implementation / Reasoning	31.9%	62.5%	3m
252	Meeting Rooms	Easy	Greedy	Greedy	59.4%	62.5%	3m
125	Valid Palindrome	Easy	Strings	Hashing / Sliding Window	53.3%	62.5%	3m
48	Rotate Image	Medium	Arrays	Sorting / Prefix / Scan	80.1%	62.5%	3m
72	Edit Distance	Medium	Dynamic Programming	State Transition	60.6%	62.5%	3m
23	Merge k Sorted Lists	Hard	Arrays; Linked List; Heap	Sorting / Prefix / Scan; Two Pointers; Priority Queue	59.6%	62.5%	3m
238	Product of Array Except Self	Medium	Arrays	Sorting / Prefix / Scan	68.9%	62.5%	6m
347	Top K Frequent Elements	Medium	Heap	Priority Queue	66.4%	62.5%	6m
981	Time Based Key-Value Store	Medium	Core DSA	Implementation / Reasoning	49.9%	62.5%	6m
53	Maximum Subarray	Medium	Arrays	Sorting / Prefix / Scan	53.3%	62.5%	6m
253	Meeting Rooms II	Medium	Greedy	Greedy	52.7%	62.5%	6m
733	Flood Fill	Easy	Core DSA	Implementation / Reasoning	68.3%	62.5%	6m
412	Fizz Buzz	Easy	Core DSA	Implementation / Reasoning	75.5%	62.5%	6m
309	Best Time to Buy and Sell Stock with Cooldown	Medium	Core DSA	Implementation / Reasoning	62.1%	62.5%	6m
112	Path Sum	Easy	Arrays; Trees	Sorting / Prefix / Scan; DFS / BFS	54.9%	62.5%	6m
1087	Brace Expansion	Medium	Core DSA	Implementation / Reasoning	66.9%	62.5%	6m
151	Reverse Words in a String	Medium	Strings	Hashing / Sliding Window	56.4%	62.5%	6m
21	Merge Two Sorted Lists	Easy	Arrays; Linked List	Sorting / Prefix / Scan; Two Pointers	68.3%	62.5%	all
28	Find the Index of the First Occurrence in a String	Easy	Strings	Hashing / Sliding Window	46.7%	62.5%	all
42	Trapping Rain Water	Hard	Core DSA	Two Pointers	67.4%	62.5%	all
70	Climbing Stairs	Easy	Dynamic Programming	State Transition	54.1%	62.5%	all
102	Binary Tree Level Order Traversal	Medium	Trees	DFS / BFS	72.7%	62.5%	all
118	Pascal's Triangle	Easy	Core DSA	Implementation / Reasoning	78.9%	62.5%	all
139	Word Break	Medium	Strings; Dynamic Programming	Hashing / Sliding Window; State Transition	49.5%	62.5%	all
149	Max Points on a Line	Hard	Core DSA	Implementation / Reasoning	30.7%	62.5%	all
165	Compare Version Numbers	Medium	Core DSA	Implementation / Reasoning	46.4%	62.5%	all
190	Reverse Bits	Easy	Core DSA	Implementation / Reasoning	68.4%	62.5%	all
191	Number of 1 Bits	Easy	Core DSA	Implementation / Reasoning	76.8%	62.5%	all
236	Lowest Common Ancestor of a Binary Tree	Medium	Trees	DFS / BFS	69.3%	62.5%	all
240	Search a 2D Matrix II	Medium	Arrays; Binary Search	Sorting / Prefix / Scan; Binary Search	57.3%	62.5%	all
283	Move Zeroes	Easy	Core DSA	Two Pointers	63.8%	62.5%	all
348	Design Tic-Tac-Toe	Medium	Design	Data Structure Design	58.7%	62.5%	all
383	Ransom Note	Easy	Core DSA	Implementation / Reasoning	66.0%	62.5%	all
443	String Compression	Medium	Strings	Hashing / Sliding Window	60.0%	62.5%	all
706	Design HashMap	Easy	Design	Data Structure Design	66.6%	62.5%	all
1	Two Sum	Easy	Arrays	Sorting / Prefix / Scan; Two Pointers	57.5%	50.0%	3m
1146	Snapshot Array	Medium	Arrays	Sorting / Prefix / Scan	36.8%	50.0%	3m
207	Course Schedule	Medium	Graphs	BFS / DFS / Topological Sort	51.4%	50.0%	3m
567	Permutation in String	Medium	Strings; Backtracking	Hashing / Sliding Window; Sliding Window; Backtracking	48.9%	50.0%	3m
328	Odd Even Linked List	Medium	Linked List	Two Pointers	62.5%	50.0%	3m
208	Implement Trie (Prefix Tree)	Medium	Trees	DFS / BFS	69.5%	50.0%	3m
17	Letter Combinations of a Phone Number	Medium	Strings; Backtracking	Hashing / Sliding Window; Backtracking	66.1%	50.0%	3m
314	Binary Tree Vertical Order Traversal	Medium	Trees	DFS / BFS	57.8%	50.0%	3m
635	Design Log Storage System	Medium	Design	Data Structure Design	59.6%	50.0%	3m
15	3Sum	Medium	Arrays	Sorting / Prefix / Scan	39.1%	50.0%	3m
863	All Nodes Distance K in Binary Tree	Medium	Trees	DFS / BFS	67.7%	50.0%	3m
621	Task Scheduler	Medium	Greedy	Greedy	63.1%	50.0%	3m
36	Valid Sudoku	Medium	Strings; Backtracking	Hashing / Sliding Window; Backtracking	64.5%	50.0%	6m
295	Find Median from Data Stream	Hard	Heap	Priority Queue	54.5%	50.0%	6m
108	Convert Sorted Array to Binary Search Tree	Easy	Arrays; Trees; Binary Search	Sorting / Prefix / Scan; DFS / BFS; Binary Search	75.6%	50.0%	6m
155	Min Stack	Medium	Stack / Queue	Monotonic Stack / Simulation	58.2%	50.0%	6m
10	Regular Expression Matching	Hard	Core DSA	Implementation / Reasoning	31.0%	50.0%	6m
2435	Paths in Matrix Whose Sum Is Divisible by K	Hard	Arrays	Sorting / Prefix / Scan	58.8%	50.0%	6m
277	Find the Celebrity	Medium	Core DSA	Implementation / Reasoning	49.0%	50.0%	6m
215	Kth Largest Element in an Array	Medium	Arrays; Heap	Sorting / Prefix / Scan; Priority Queue	68.9%	50.0%	6m
5	Longest Palindromic Substring	Medium	Strings; Trees	Hashing / Sliding Window; DFS / BFS	37.8%	50.0%	6m
4	Median of Two Sorted Arrays	Hard	Arrays; Heap	Sorting / Prefix / Scan; Priority Queue	46.6%	50.0%	6m
11	Container With Most Water	Medium	Core DSA	Two Pointers	60.0%	50.0%	6m
22	Generate Parentheses	Medium	Strings	Hashing / Sliding Window	78.7%	50.0%	all
33	Search in Rotated Sorted Array	Medium	Arrays; Binary Search	Sorting / Prefix / Scan; Binary Search	44.9%	50.0%	all
55	Jump Game	Medium	Greedy	Greedy	40.9%	50.0%	all
69	Sqrt(x)	Easy	Binary Search	Binary Search	41.8%	50.0%	all
104	Maximum Depth of Binary Tree	Easy	Arrays; Trees	Sorting / Prefix / Scan; DFS / BFS	78.2%	50.0%	all
167	Two Sum II - Input Array Is Sorted	Medium	Arrays	Sorting / Prefix / Scan; Two Pointers	65.1%	50.0%	all
221	Maximal Square	Medium	Core DSA	Implementation / Reasoning	50.3%	50.0%	all
237	Delete Node in a Linked List	Medium	Trees; Linked List	DFS / BFS; Two Pointers	83.9%	50.0%	all
257	Binary Tree Paths	Easy	Trees	DFS / BFS	68.7%	50.0%	all
297	Serialize and Deserialize Binary Tree	Hard	Trees; Design	DFS / BFS; Data Structure Design	60.8%	50.0%	all
387	First Unique Character in a String	Easy	Strings	Hashing / Sliding Window	65.5%	50.0%	all
394	Decode String	Medium	Strings; Dynamic Programming; Stack / Queue	Hashing / Sliding Window; State Transition; Monotonic Stack / Simulation	62.6%	50.0%	all
565	Array Nesting	Medium	Arrays	Sorting / Prefix / Scan	56.6%	50.0%	all
658	Find K Closest Elements	Medium	Core DSA	Implementation / Reasoning	49.7%	50.0%	all
714	Best Time to Buy and Sell Stock with Transaction Fee	Medium	Core DSA	Implementation / Reasoning	72.0%	50.0%	all
509	Fibonacci Number	Easy	Core DSA	Implementation / Reasoning	74.1%	50.0%	all
996	Number of Squareful Arrays	Hard	Arrays	Sorting / Prefix / Scan	51.5%	50.0%	all
1047	Remove All Adjacent Duplicates In String	Easy	Arrays; Strings	Sorting / Prefix / Scan; Hashing / Sliding Window	73.2%	50.0%	all
1275	Find Winner on a Tic Tac Toe Game	Easy	Core DSA	Implementation / Reasoning	54.6%	50.0%	all
2023	Number of Pairs of Strings With Concatenation Equal to Target	Medium	Strings	Hashing / Sliding Window	75.4%	50.0%	all
2397	Maximum Rows Covered by Columns	Medium	Arrays	Sorting / Prefix / Scan	58.0%	50.0%	all
2972	Count the Number of Incremovable Subarrays II	Hard	Arrays	Sorting / Prefix / Scan	40.2%	50.0%	all
2970	Count the Number of Incremovable Subarrays I	Easy	Arrays	Sorting / Prefix / Scan	56.5%	50.0%	all
3030	Find the Grid of Region Average	Medium	Core DSA	Implementation / Reasoning	43.5%	50.0%	all
3522	Calculate Score After Performing Instructions	Medium	Core DSA	Implementation / Reasoning	57.1%	50.0%	all
1606	Find Servers That Handled Most Number of Requests	Hard	Core DSA	Implementation / Reasoning	45.4%	50.0%	all
3	Longest Substring Without Repeating Characters	Medium	Strings; Trees	Hashing / Sliding Window; DFS / BFS; Sliding Window	39.1%	37.5%	6m
189	Rotate Array	Medium	Arrays	Sorting / Prefix / Scan	44.9%	37.5%	6m
622	Design Circular Queue	Medium	Stack / Queue; Design	Monotonic Stack / Simulation; Data Structure Design	54.7%	37.5%	6m
127	Word Ladder	Hard	Strings	Hashing / Sliding Window	45.6%	37.5%	6m
128	Longest Consecutive Sequence	Medium	Core DSA	Implementation / Reasoning	47.1%	37.5%	6m
26	Remove Duplicates from Sorted Array	Easy	Arrays	Sorting / Prefix / Scan; Two Pointers	62.8%	37.5%	6m
284	Peeking Iterator	Medium	Design	Data Structure Design	61.5%	37.5%	6m
18	4Sum	Medium	Arrays	Sorting / Prefix / Scan	40.6%	37.5%	6m
57	Insert Interval	Medium	Arrays	Sorting / Prefix / Scan	45.2%	37.5%	6m
109	Convert Sorted List to Binary Search Tree	Medium	Arrays; Trees; Linked List; Binary Search	Sorting / Prefix / Scan; DFS / BFS; Two Pointers; Binary Search	66.6%	37.5%	6m
217	Contains Duplicate	Easy	Arrays	Sorting / Prefix / Scan	64.4%	37.5%	6m
341	Flatten Nested List Iterator	Medium	Linked List; Design	Two Pointers; Data Structure Design	65.7%	37.5%	6m
535	Encode and Decode TinyURL	Medium	Dynamic Programming	State Transition	86.6%	37.5%	6m
273	Integer to English Words	Hard	Strings	Hashing / Sliding Window	35.0%	37.5%	6m
329	Longest Increasing Path in a Matrix	Hard	Arrays; Dynamic Programming	Sorting / Prefix / Scan; State Transition	56.6%	37.5%	6m
134	Gas Station	Medium	Greedy	Greedy	48.0%	37.5%	6m
2	Add Two Numbers	Medium	Core DSA	Implementation / Reasoning	48.5%	37.5%	6m
895	Maximum Frequency Stack	Hard	Arrays; Stack / Queue	Sorting / Prefix / Scan; Monotonic Stack / Simulation	66.8%	37.5%	6m
19	Remove Nth Node From End of List	Medium	Trees; Linked List	DFS / BFS; Two Pointers	51.6%	37.5%	6m
1197	Minimum Knight Moves	Medium	Arrays	Sorting / Prefix / Scan	42.0%	37.5%	6m
931	Minimum Falling Path Sum	Medium	Arrays; Trees	Sorting / Prefix / Scan; DFS / BFS	60.8%	37.5%	6m
918	Maximum Sum Circular Subarray	Medium	Arrays	Sorting / Prefix / Scan	50.2%	37.5%	6m
232	Implement Queue using Stacks	Easy	Stack / Queue	Monotonic Stack / Simulation	69.8%	37.5%	6m
88	Merge Sorted Array	Easy	Arrays	Sorting / Prefix / Scan	54.9%	37.5%	6m
787	Cheapest Flights Within K Stops	Medium	Heap	Priority Queue	41.8%	37.5%	6m
432	All O`one Data Structure	Hard	Core DSA	Implementation / Reasoning	44.3%	37.5%	6m
8	String to Integer (atoi)	Medium	Strings	Hashing / Sliding Window	21.0%	37.5%	all
13	Roman to Integer	Easy	Strings	Hashing / Sliding Window	66.6%	37.5%	all
39	Combination Sum	Medium	Arrays; Backtracking	Sorting / Prefix / Scan; Backtracking	76.5%	37.5%	all
46	Permutations	Medium	Backtracking	Backtracking	81.9%	37.5%	all
68	Text Justification	Hard	Core DSA	Implementation / Reasoning	51.2%	37.5%	all
71	Simplify Path	Medium	Core DSA	Implementation / Reasoning	50.6%	37.5%	all
73	Set Matrix Zeroes	Medium	Arrays	Sorting / Prefix / Scan	62.9%	37.5%	all
74	Search a 2D Matrix	Medium	Arrays; Binary Search	Sorting / Prefix / Scan; Binary Search	53.9%	37.5%	all
79	Word Search	Medium	Strings; Binary Search	Hashing / Sliding Window; Binary Search	47.4%	37.5%	all
92	Reverse Linked List II	Medium	Linked List	Two Pointers	51.5%	37.5%	all
97	Interleaving String	Medium	Strings	Hashing / Sliding Window	44.0%	37.5%	all
123	Best Time to Buy and Sell Stock III	Hard	Core DSA	Implementation / Reasoning	53.7%	37.5%	all
124	Binary Tree Maximum Path Sum	Hard	Arrays; Trees	Sorting / Prefix / Scan; DFS / BFS	42.3%	37.5%	all
153	Find Minimum in Rotated Sorted Array	Medium	Arrays; Binary Search	Sorting / Prefix / Scan; Binary Search	54.7%	37.5%	all
162	Find Peak Element	Medium	Binary Search	Binary Search	47.0%	37.5%	all
188	Best Time to Buy and Sell Stock IV	Hard	Core DSA	Implementation / Reasoning	50.1%	37.5%	all
198	House Robber	Medium	Dynamic Programming	State Transition	53.2%	37.5%	all
202	Happy Number	Easy	Core DSA	Implementation / Reasoning	59.7%	37.5%	all
213	House Robber II	Medium	Dynamic Programming	State Transition	44.9%	37.5%	all
224	Basic Calculator	Hard	Stack / Queue	Monotonic Stack / Simulation	46.9%	37.5%	all
239	Sliding Window Maximum	Hard	Arrays	Sorting / Prefix / Scan; Sliding Window	48.8%	37.5%	all
242	Valid Anagram	Easy	Strings	Hashing / Sliding Window	68.1%	37.5%	all
268	Missing Number	Easy	Arrays	Sorting / Prefix / Scan	72.0%	37.5%	all
274	H-Index	Medium	Core DSA	Implementation / Reasoning	41.4%	37.5%	all
322	Coin Change	Medium	Dynamic Programming	State Transition	48.4%	37.5%	all
344	Reverse String	Easy	Strings	Hashing / Sliding Window	80.8%	37.5%	all
378	Kth Smallest Element in a Sorted Matrix	Medium	Arrays; Heap	Sorting / Prefix / Scan; Priority Queue	64.6%	37.5%	all
424	Longest Repeating Character Replacement	Medium	Strings	Hashing / Sliding Window	59.7%	37.5%	all
460	LFU Cache	Hard	Design	Data Structure Design	49.2%	37.5%	all
468	Validate IP Address	Medium	Strings	Hashing / Sliding Window	28.3%	37.5%	all
647	Palindromic Substrings	Medium	Strings; Trees	Hashing / Sliding Window; DFS / BFS	72.8%	37.5%	all
680	Valid Palindrome II	Easy	Strings	Hashing / Sliding Window	44.3%	37.5%	all
876	Middle of the Linked List	Easy	Linked List	Two Pointers	81.8%	37.5%	all
909	Snakes and Ladders	Medium	Core DSA	Implementation / Reasoning	48.1%	37.5%	all
994	Rotting Oranges	Medium	Core DSA	Implementation / Reasoning	58.7%	37.5%	all
1011	Capacity To Ship Packages Within D Days	Medium	Binary Search	Binary Search	73.9%	37.5%	all
3074	Apple Redistribution into Boxes	Easy	Core DSA	Implementation / Reasoning	78.6%	37.5%	all
688	Knight Probability in Chessboard	Medium	Core DSA	Implementation / Reasoning	57.0%	37.5%	all
1650	Lowest Common Ancestor of a Binary Tree III	Medium	Trees	DFS / BFS	83.0%	37.5%	all
855	Exam Room	Medium	Core DSA	Implementation / Reasoning	43.5%	37.5%	all
2591	Distribute Money to Maximum Children	Easy	Arrays	Sorting / Prefix / Scan	20.6%	37.5%	all
269	Alien Dictionary	Hard	Graphs	BFS / DFS / Topological Sort	37.2%	37.5%	all
841	Keys and Rooms	Medium	Core DSA	Implementation / Reasoning	75.8%	37.5%	all
211	Design Add and Search Words Data Structure	Medium	Strings; Binary Search; Design	Hashing / Sliding Window; Binary Search; Data Structure Design	48.5%	37.5%	all
2065	Maximum Path Quality of a Graph	Hard	Arrays; Graphs	Sorting / Prefix / Scan; BFS / DFS / Topological Sort	62.2%	37.5%	all
6	Zigzag Conversion	Medium	Core DSA	Implementation / Reasoning	54.2%	25.0%	all
25	Reverse Nodes in k-Group	Hard	Trees; Linked List	DFS / BFS; Two Pointers	66.1%	25.0%	all
27	Remove Element	Easy	Core DSA	Implementation / Reasoning	61.8%	25.0%	all
41	First Missing Positive	Hard	Arrays	Sorting / Prefix / Scan	42.9%	25.0%	all
45	Jump Game II	Medium	Greedy	Greedy	42.9%	25.0%	all
47	Permutations II	Medium	Backtracking	Backtracking	63.5%	25.0%	all
67	Add Binary	Easy	Core DSA	Implementation / Reasoning	58.1%	25.0%	all
75	Sort Colors	Medium	Arrays	Sorting / Prefix / Scan	69.6%	25.0%	all
76	Minimum Window Substring	Hard	Arrays; Strings; Trees	Sorting / Prefix / Scan; Hashing / Sliding Window; DFS / BFS; Sliding Window	47.5%	25.0%	all
84	Largest Rectangle in Histogram	Hard	Core DSA	Implementation / Reasoning	49.9%	25.0%	all
90	Subsets II	Medium	Backtracking	Backtracking	61.3%	25.0%	all
91	Decode Ways	Medium	Dynamic Programming	State Transition	38.0%	25.0%	all
98	Validate Binary Search Tree	Medium	Strings; Trees; Binary Search	Hashing / Sliding Window; DFS / BFS; Binary Search	35.8%	25.0%	all
100	Same Tree	Easy	Trees	DFS / BFS	67.1%	25.0%	all
101	Symmetric Tree	Easy	Trees	DFS / BFS	61.2%	25.0%	all
138	Copy List with Random Pointer	Medium	Linked List	Two Pointers	62.9%	25.0%	all
143	Reorder List	Medium	Linked List	Two Pointers	65.3%	25.0%	all
150	Evaluate Reverse Polish Notation	Medium	Core DSA	Implementation / Reasoning	57.8%	25.0%	all
160	Intersection of Two Linked Lists	Easy	Linked List	Two Pointers	63.7%	25.0%	all
176	Second Highest Salary	Medium	Core DSA	Implementation / Reasoning	47.0%	25.0%	all
203	Remove Linked List Elements	Easy	Linked List	Two Pointers	54.5%	25.0%	all
204	Count Primes	Medium	Core DSA	Implementation / Reasoning	36.1%	25.0%	all
218	The Skyline Problem	Hard	Core DSA	Implementation / Reasoning	45.4%	25.0%	all
219	Contains Duplicate II	Easy	Arrays	Sorting / Prefix / Scan	51.3%	25.0%	all

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