Google Coding Interview Questions

Graph, systems thinking, and clean complexity analysis are heavily tested.

#	Title	Difficulty	Topics
1	Two Sum	Easy	hash table
4	Median of Two Sorted Arrays	Hard	binary search
11	Container With Most Water	Medium	greedy
20	Valid Parentheses	Easy	stack
22	Generate Parentheses	Medium	backtracking
23	Merge k Sorted Lists	Hard	linked list
42	Trapping Rain Water	Hard	greedy
45	Jump Game II	Hard	greedy
50	Pow(x, n)	Medium	math
55	Jump Game	Medium	greedy
56	Merge Intervals	Hard	sort
57	Insert Interval	Hard	sort
66	Plus One	Easy	array
72	Edit Distance	Hard	dynamic programming
76	Minimum Window Substring	Hard	hash table
84	Largest Rectangle in Histogram	Hard	stack
85	Maximal Rectangle	Hard	stack
95	Unique Binary Search Trees II	Medium	recursion
97	Interleaving String	Hard	dynamic programming
115	Distinct Subsequences	Hard	dynamic programming
124	Binary Tree Maximum Path Sum	Hard	recursion
128	Longest Consecutive Sequence	Hard	array
130	Surrounded Regions	Medium	breadth first search
131	Palindrome Partitioning	Medium	backtracking
132	Palindrome Partitioning II	Hard	dynamic programming
133	Clone Graph	Medium	breadth first search
134	Gas Station	Medium	greedy
135	Candy	Hard	greedy
139	Word Break	Medium	dynamic programming
140	Word Break II	Hard	backtracking
146	LRU Cache	Hard	design
147	Insertion Sort List	Medium	sort
148	Sort List	Medium	sort
149	Max Points on a Line	Hard	hash table
153	Find Minimum in Rotated Sorted Array	Medium	binary search
154	Find Minimum in Rotated Sorted Array II	Hard	binary search
155	Min Stack	Easy	stack
162	Find Peak Element	Medium	binary search
164	Maximum Gap	Hard	sort
166	Fraction to Recurring Decimal	Medium	math
173	Binary Search Tree Iterator	Medium	design
188	Best Time to Buy and Sell Stock IV	Hard	dynamic programming
198	House Robber	Easy	dynamic programming
200	Number of Islands	Medium	depth first search
202	Happy Number	Easy	hash table
207	Course Schedule	Medium	breadth first search
208	Implement Trie (Prefix Tree)	Medium	tree
209	Minimum Size Subarray Sum	Medium	two pointers
210	Course Schedule II	Medium	breadth first search
213	House Robber II	Medium	dynamic programming
218	The Skyline Problem	Hard	sort
221	Maximal Square	Medium	dynamic programming
222	Count Complete Tree Nodes	Medium	binary search
224	Basic Calculator	Hard	stack
230	Kth Smallest Element in a BST	Medium	binary search tree
231	Power of Two	Easy	bit manipulation
235	Lowest Common Ancestor of a Binary Search Tree	Easy	binary search tree
239	Sliding Window Maximum	Hard	queue
240	Search a 2D Matrix II	Medium	array
257	Binary Tree Paths	Easy	depth first search
264	Ugly Number II	Medium	binary heap
278	First Bad Version	Easy	binary search
289	Game of Life	Medium	array
299	Bulls and Cows	Easy	hash table
300	Longest Increasing Subsequence	Medium	binary search
304	Range Sum Query 2D - Immutable	Medium	dynamic programming
309	Best Time to Buy and Sell Stock with Cooldown	Medium	dynamic programming
310	Minimum Height Trees	Medium	breadth first search
312	Burst Balloons	Hard	dynamic programming
313	Super Ugly Number	Medium	binary heap
316	Remove Duplicate Letters	Hard	greedy
318	Maximum Product of Word Lengths	Medium	bit manipulation
319	Bulb Switcher	Medium	math
321	Create Maximum Number	Hard	greedy
324	Wiggle Sort II	Medium	sort
326	Power of Three	Easy	math
327	Count of Range Sum	Hard	recursion
329	Longest Increasing Path in a Matrix	Hard	depth first search
330	Patching Array	Hard	greedy
332	Reconstruct Itinerary	Medium	graph
335	Self Crossing	Hard	math
336	Palindrome Pairs	Hard	hash table
340	Longest Substring with At Most K Distinct Characters	Hard	hash table
341	Flatten Nested List Iterator	Medium	stack
345	Reverse Vowels of a String	Easy	two pointers
346	Moving Average from Data Stream	Easy	queue
352	Data Stream as Disjoint Intervals	Hard	binary search tree
353	Design Snake Game	Medium	design
354	Russian Doll Envelopes	Hard	binary search
373	Find K Pairs with Smallest Sums	Medium	binary heap
374	Guess Number Higher or Lower	Easy	binary search
378	Kth Smallest Element in a Sorted Matrix	Medium	binary heap
380	Insert Delete GetRandom O(1)	Hard	design
382	Linked List Random Node	Medium	math
384	Shuffle an Array	Medium	array
385	Mini Parser	Medium	stack
386	Lexicographical Numbers	Medium	math
388	Longest Absolute File Path	Medium	hash table
389	Find the Difference	Easy	bit manipulation
390	Elimination Game	Medium	math
391	Perfect Rectangle	Hard	math
392	Is Subsequence	Medium	greedy
393	UTF-8 Validation	Medium	bit manipulation
394	Decode String	Medium	stack
417	Pacific Atlantic Water Flow	Medium	depth first search
419	Battleships in a Board	Medium	array
420	Strong Password Checker	Hard	string
424	Longest Repeating Character Replacement	Medium	two pointers
436	Find Right Interval	Medium	binary search
438	Find All Anagrams in a String	Easy	hash table
441	Arranging Coins	Easy	math
448	Find All Numbers Disappeared in an Array	Easy	array
451	Sort Characters By Frequency	Medium	sort
458	Poor Pigs	Easy	math
459	Repeated Substring Pattern	Easy	string
463	Island Perimeter	Easy	array
464	Can I Win	Medium	depth first search
465	Optimal Account Balancing	Hard	dynamic programming
466	Count The Repetitions	Hard	dynamic programming
475	Heaters	Easy	binary search
480	Sliding Window Median	Hard	binary heap
481	Magical String	Medium	string
482	License Key Formatting	Easy	string
483	Smallest Good Base	Hard	math
485	Max Consecutive Ones	Easy	array
486	Predict the Winner	Medium	dynamic programming
496	Next Greater Element I	Easy	stack
503	Next Greater Element II	Medium	stack
514	Freedom Trail	Hard	dynamic programming
521	Longest Uncommon Subsequence I	Easy	string
522	Longest Uncommon Subsequence II	Medium	string
524	Longest Word in Dictionary through Deleting	Medium	string
525	Contiguous Array	Medium	hash table
526	Beautiful Arrangement	Medium	backtracking
529	Minesweeper	Medium	tree
530	Minimum Absolute Difference in BST	Easy	binary search tree
535	Encode and Decode TinyURL	Medium	design
540	Single Element in a Sorted Array	Medium	binary search
543	Diameter of Binary Tree	Easy	tree
546	Remove Boxes	Hard	dynamic programming
547	Friend Circles	Medium	depth first search
560	Subarray Sum Equals K	Medium	hash table
563	Binary Tree Tilt	Easy	tree
621	Task Scheduler	Medium	greedy
630	Course Schedule III	Hard	greedy
643	Maximum Average Subarray I	Easy	array
644	Maximum Average Subarray II	Hard	array
647	Palindromic Substrings	Medium	string
651	4 Keys Keyboard	Medium	math
652	Find Duplicate Subtrees	Medium	tree
653	Two Sum IV - Input is a BST	Easy	tree
658	Find K Closest Elements	Medium	binary search
659	Split Array into Consecutive Subsequences	Medium	greedy
660	Remove 9	Hard	math
662	Maximum Width of Binary Tree	Medium	tree
664	Strange Printer	Hard	dynamic programming
683	K Empty Slots	Hard	array
688	Knight Probability in Chessboard	Medium	dynamic programming
689	Maximum Sum of 3 Non-Overlapping Subarrays	Hard	dynamic programming
690	Employee Importance	Easy	depth first search
691	Stickers to Spell Word	Hard	dynamic programming
710	Random Pick with Blacklist	Hard	binary search
759	Employee Free Time	Hard	greedy
760	Find Anagram Mappings	Easy	hash table
761	Special Binary String	Hard	recursion
763	Partition Labels	Medium	greedy
764	Largest Plus Sign	Medium	dynamic programming
765	Couples Holding Hands	Hard	graph
787	Cheapest Flights Within K Stops	Medium	breadth first search
813	Largest Sum of Averages	Medium	dynamic programming
815	Bus Routes	Medium	breadth first search
816	Ambiguous Coordinates	Medium	string
817	Linked List Components	Medium	linked list
818	Race Car	Hard	dynamic programming
819	Most Common Word	Easy	string
820	Short Encoding of Words	Medium	string
822	Card Flipping Game	Medium	hash table
823	Binary Trees With Factors	Medium	dynamic programming
852	Peak Index in a Mountain Array	Easy	binary search
853	Car Fleet	Medium	stack
854	K-Similar Strings	Hard	breadth first search
855	Exam Room	Medium	binary heap
857	Minimum Cost to Hire K Workers	Hard	binary heap
858	Mirror Reflection	Medium	math
859	Buddy Strings	Easy	string
861	Score After Flipping Matrix	Medium	greedy
862	Shortest Subarray with Sum at Least K	Hard	two pointers
875	Koko Eating Bananas	Medium	binary search
890	Find and Replace Pattern	Medium	string
891	Sum of Subsequence Widths	Hard	math
901	Online Stock Span	Medium	stack
902	Numbers At Most N Given Digit Set	Hard	math
905	Sort Array By Parity	Easy	array
906	Super Palindromes	Hard	math
907	Sum of Subarray Minimums	Medium	math
908	Smallest Range I	Easy	math
909	Snakes and Ladders	Medium	array
910	Smallest Range II	Medium	math
911	Online Election	Medium	binary search
918	Maximum Sum Circular Subarray	Medium	array
919	Complete Binary Tree Inserter	Medium	tree
924	Minimize Malware Spread	Hard	graph
925	Long Pressed Name	Easy	string
926	Flip String to Monotone Increasing	Medium	dynamic programming
927	Three Equal Parts	Hard	array
928	Minimize Malware Spread II	Hard	graph
929	Unique Email Addresses	Easy	string
931	Minimum Falling Path Sum	Medium	dynamic programming
932	Beautiful Array	Medium	array
933	Number of Recent Calls	Easy	queue
934	Shortest Bridge	Medium	breadth first search
939	Minimum Area Rectangle	Medium	string
940	Distinct Subsequences II	Hard	dynamic programming
941	Valid Mountain Array	Easy	array
942	DI String Match	Easy	string
944	Delete Columns to Make Sorted	Medium	string
945	Minimum Increment to Make Array Unique	Medium	array
946	Validate Stack Sequences	Medium	stack
947	Most Stones Removed with Same Row or Column	Medium	array
948	Bag of Tokens	Medium	greedy
949	Largest Time for Given Digits	Easy	array
950	Reveal Cards In Increasing Order	Medium	array
951	Flip Equivalent Binary Trees	Medium	tree
952	Largest Component Size by Common Factor	Hard	array
953	Verifying an Alien Dictionary	Easy	string
955	Delete Columns to Make Sorted II	Medium	string
956	Tallest Billboard	Hard	dynamic programming
958	Check Completeness of a Binary Tree	Medium	tree
959	Regions Cut By Slashes	Medium	graph
962	Maximum Width Ramp	Medium	greedy
983	Minimum Cost For Tickets	Medium	dynamic programming