LeetCode

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"For coding interview preparation, LeetCode is one of the best online resource providing a rich library of more than 300 real coding interview questions for you to practice from using one of the 7 supported languages - C, C++, Java, Python, C#, JavaScript, Ruby."

Algorithms

#	Title	Solutions	Video	Difficulty	Tag
1297	Maximum Number of Occurrences of a Substring	Solution		Medium
1296	Divide Array in Sets of K Consecutive Numbers	Solution		Medium
1295	Find Numbers with Even Number of Digits	Solution		Easy
1290	Convert Binary Number in a Linked List to Integer	Solution		Easy
1287	Element Appearing More Than 25% In Sorted Array	Solution		Easy
1282	Group the People Given the Group Size They Belong To	Solution	📺	Medium
1281	Subtract the Product and Sum of Digits of an Integer	Solution		Easy
1277	Count Square Submatrices with All Ones	Solution		Medium
1271	Hexspeak	Solution		Easy
1267	Count Servers that Communicate	Solution		Medium
1266	Minimum Time Visiting All Points	Solution		Easy
1260	Shift 2D Grid	Solution	📺	Easy
1252	Cells with Odd Values in a Matrix	Solution		Easy
1237	Find Positive Integer Solution for a Given Equation	Solution		Easy
1243	Array Transformation	Solution	📺	Easy
1232	Check If It Is a Straight Line	Solution		Easy
1228	Missing Number In Arithmetic Progression	Solution		Easy
1217	Play with Chips	Solution		Easy
1213	Intersection of Three Sorted Arrays	Solution	📺	Easy
1207	Unique Number of Occurrences	Solution	📺	Easy
1200	Minimum Absolute Difference	Solution	📺	Easy
1198	Find Smallest Common Element in All Rows	Solution	📺	Easy
1196	How Many Apples Can You Put into the Basket	Solution		Easy
1189	Maximum Number of Balloons	Solution		Easy
1185	Day of the Week	Solution		Easy
1184	Distance Between Bus Stops	Solution	📺	Easy
1165	Single-Row Keyboard	Solution		Easy
1160	Find Words That Can Be Formed by Characters	Solution		Easy
1154	Day of the Year	Solution		Easy
1150	Check If a Number Is Majority Element in a Sorted Array	Solution		Easy
1137	N-th Tribonacci Number	Solution		Easy
1134	Armstrong Number	Solution	📺	Easy
1133	Largest Unique Number	Solution		Easy
1128	Number of Equivalent Domino Pairs	Solution	📺	Easy
1122	Relative Sort Array	Solution		Easy
1170	Compare Strings by Frequency of the Smallest Character	Solution		Easy
1119	Remove Vowels from a String	Solution	📺	Easy
1108	Defanging an IP Address	Solution	📺	Easy
1099	Two Sum Less Than K	Solution	📺	Easy
1089	Duplicate Zeros	Solution		Easy
1086	High Five	Solution	📺	Easy
1085	Sum of Digits in the Minimum Number	Solution	📺	Easy
1079	Letter Tile Possibilities	Solution		Medium
1078	Occurrences After Bigram	Solution		Easy
1071	Greatest Common Divisor of Strings	Solution		Easy
1065	Index Pairs of a String	Solution		Medium
1056	Confusing Number	Solution		Easy
1055	Fixed Point	Solution		Easy
1051	Height Checker	Solution		Easy
1047	Remove All Adjacent Duplicates In String	Solution		Easy
1043	Partition Array for Maximum Sum	Solution		Medium	DP
1038	Binary Search Tree to Greater Sum Tree	Solution		Medium	DFS, tree
1037	Valid Boomerang	Solution		Easy	Math
1033	Moving Stones Until Consecutive	Solution		Easy	Math
1030	Matrix Cells in Distance Order	Solution		Easy
1029	Two City Scheduling	Solution		Easy
1022	Sum of Root To Leaf Binary Numbers	Solution		Easy
1021	Remove Outermost Parentheses	Solution		Easy
1020	Number of Enclaves	Solution		Medium	Graph, DFS, BFS, recursion
1018	Binary Prefix Divisible By 5	Solution		Easy
1014	Best Sightseeing Pair	Solution		Medium
1013	Partition Array Into Three Parts With Equal Sum	Solution		Easy
1011	Capacity To Ship Packages Within D Days	Solution		Medium	Binary Search
1010	Pairs of Songs With Total Durations Divisible by 60	Solution		Easy
1009	Complement of Base 10 Integer	Solution		Easy
1008	Construct Binary Search Tree from Preorder Traversal	Solution		Medium	Recursion
1003	Check If Word Is Valid After Substitutions	Solution		Medium
1002	Find Common Characters	Solution		Easy
999	Available Captures for Rook	Solution		Easy
997	Find the Town Judge	Solution		Easy
994	Rotting Oranges	Solution		Easy	BFS
993	Cousins in Binary Tree	Solution		Easy	Tree, BFS
989	Add to Array-Form of Integer	Solution		Easy	Array
987	Vertical Order Traversal of a Binary Tree	Solution		Medium	Recursion
985	Sum of Even Numbers After Queries	Solution		Easy	Array
979	Distribute Coins in Binary Tree	Solution		Medium	Recursion
977	Squares of a Sorted Array	Solution		Easy	Array
976	Largest Perimeter Triangle	Solution		Easy	Math Array
974	Subarray Sums Divisible by K	Solution		Medium	Array
973	K Closest Points to Origin	Solution		Easy	Math Sort
970	Powerful Integers	Solution		Easy	Math
966	Vowel Spellchecker	Solution		Medium	Hash Table, String
965	Univalued Binary Tree	Solution		Easy	DFS, recursion
961	N-Repeated Element in Size 2N Array	Solution		Easy
954	Array of Doubled Pairs	Solution	📺	Medium
953	Verifying an Alien Dictionary	Solution		Easy
951	Flip Equivalent Binary Trees	Solution		Medium	Tree, DFS, recursion
950	Reveal Cards In Increasing Order	Solution		Medium
944	Delete Columns to Make Sorted	Solution		Easy
942	DI String Match	Solution		Easy
941	Valid Mountain Array	Solution		Easy
938	Range Sum of BST	Solution		Medium	BST, recursion, DFS
937	Reorder Log Files	Solution		Easy
935	Knight Dialer	Solution		Medium
933	Number of Recent Calls	Solution		Easy
929	Unique Email Addresses	Solution		Easy
925	Long Pressed Name	Solution		Easy
922	Sort Array By Parity II	Solution		Easy
917	Reverse Only Letters	Solution		Easy
914	X of a Kind in a Deck of Cards	Solution		Easy
912	Sort an Array	Solution		Easy
908	Smallest Range I	Solution		Easy
900	RLE Iterator	Solution		Medium
897	Increasing Order Search Tree	Solution		Easy	DFS, recursion
896	Monotonic Array	Solution		Easy
890	Find and Replace Pattern	Solution		Medium
893	Groups of Special-Equivalent Strings	Solution		Easy
888	Fair Candy Swap	Solution		Easy
885	Spiral Matrix III	Solution		Medium
884	Uncommon Words from Two Sentences	Solution		Easy
876	Middle of the Linked List	Solution		Easy
872	Leaf-Similar Trees	Solution		Easy	DFS, recursion
868	Binary Gap	Solution		Easy
867	Transpose Matrix	Solution		Easy
860	Lemonade Change	Solution		Easy
859	Buddy Strings	Solution		Easy
852	Peak Index in a Mountain Array	Solution		Easy
849	Maximize Distance to Closest Person	Solution		Easy
844	Backspace String Compare	Solution		Easy
840	Magic Squares In Grid	Solution		Easy
836	Rectangle Overlap	Solution		Easy
832	Flipping an Image	Solution		Easy
830	Positions of Large Groups	Solution		Easy
824	Goat Latin	Solution		Easy
821	Shortest Distance to a Character	Solution		Easy
819	Most Common Word	Solution		Easy	HashMap
814	Binary Tree Pruning	Solution		Medium	recursion, DFS
811	Subdomain Visit Count	Solution		Easy	HashMap
806	Number of Lines To Write String	Solution		Easy
804	Unique Morse Code Words	Solution		Easy
800	Similar RGB Color	Solution		Easy
799	Champagne Tower	Solution		Medium
796	Rotate String	Solution		Easy
791	Custom Sort String	Solution		Medium
789	Escape The Ghosts	Solution		Medium	Math
788	Rotated Digits	Solution		Easy
784	Letter Case Permutation	Solution		Easy
783	Minimum Distance Between BST Nodes	Solution		Easy
779	K-th Symbol in Grammar	Solution		Medium
776	Split BST	Solution		Medium	Recursion
771	Jewels and Stones	Solution		Easy
769	Max Chunks To Make Sorted	Solution		Medium	Array
767	Reorganize String	Solution		Medium
766	Toeplitz Matrix	Solution		Easy
765	Couples Holding Hands	Solution		Hard
764	Largest Plus Sign	Solution		Medium	DP
763	Partition Labels	Solution		Medium
762	Prime Number of Set Bits in Binary Representation	Solution		Easy
760	Find Anagram Mappings	Solution		Easy
758	Bold Words in String	Solution		Easy
756	Pyramid Transition Matrix	Solution		Medium	Backtracking
755	Pour Water	Solution		Medium	Array
754	Reach a Number	Solution		Medium	Math
750	Number Of Corner Rectangles	Solution		Medium
748	Shortest Completing Word	Solution		Easy
747	Largest Number Greater Than Twice of Others	Solution		Easy
746	Min Cost Climbing Stairs	Solution		Easy
744	Find Smallest Letter Greater Than Target	Solution		Easy
743	Network Delay Time	Solution		Medium	Graph, Djikstra
740	Delete and Earn	Solution		Medium
739	Daily Temperatures	Solution		Medium
738	Monotone Increasing Digits	Solution		Medium
737	Sentence Similarity II	Solution		Medium	Union Find
735	Asteroid Collision	Solution		Medium	Stack
734	Sentence Similarity	Solution		Easy	HashTable
733	Flood Fill	Solution		Easy	BFS, DFS
729	My Calendar I	Solution		Medium
728	Self Dividing Numbers	Solution		Easy
727	Minimum Window Subsequence	Solution		Hard	DP
725	Split Linked List in Parts	Solution		Medium	LinkedList
724	Find Pivot Index	Solution		Easy	Array
723	Candy Crush	Solution		Medium	Array, Two Pointers
721	Accounts Merge	Solution		Medium	DFS, Union Find
720	Longest Word in Dictionary	Solution		Easy	Trie
719	Find K-th Smallest Pair Distance	Solution		Hard	Binary Search
718	Maximum Length of Repeated Subarray	Solution		Medium	DP
717	1-bit and 2-bit Characters	Solution		Easy
716	Max Stack	Solution		Hard	Design
714	Best Time to Buy and Sell Stock with Transaction Fee	Solution		Medium	DP
713	Subarray Product Less Than K	Solution		Medium
712	Minimum ASCII Delete Sum for Two Strings	Solution		Medium	DP
709	To Lower Case	Solution		Easy	String
706	Design HashMap	Solution		Easy	Design
705	Design HashSet	Solution		Easy	Design
704	Binary Search	Solution		Easy	Binary Search
703	Kth Largest Element in a Stream	Solution		Easy
701	Insert into a Binary Search Tree	Solution		Medium	DFS, recursion
700	Search in a Binary Search Tree	Solution		Easy	recusion, dfs
699	Falling Squares	Solution		Hard	Segment Tree
698	Partition to K Equal Sum Subsets	Solution		Medium	Backtracking
697	Degree of an Array	Solution		Easy
696	Count Binary Substrings	Solution		Easy
695	Max Area of Island	Solution		Easy	DFS
694	Number of Distinct Islands	Solution		Medium	DFS
693	Binary Number with Alternating Bits	Solution		Easy
692	Top K Frequent Words	Solution		Medium
691	Stickers to Spell Word	Solution		Hard	DP
690	Employee Importance	Solution		Easy	DFS
689	Maximum Sum of 3 Non-Overlapping Subarrays	Solution		Hard	DP
688	Knight Probability in Chessboard	Solution		Medium	DP
687	Longest Univalue Path	Solution		Easy	DFS
686	Repeated String Match	Solution		Easy
685	Redundant Connection II	Solution		Hard	Union Find
684	Redundant Connection	Solution		Medium	Union Find
683	K Empty Slots	Solution		Hard
682	Baseball Game	Solution		Easy
681	Next Closest Time	Solution		Medium
680	Valid Palindrome II	Solution		Easy	String
679	24 Game	Solution		Hard	Recursion
678	Valid Parenthesis String	Solution		Medium	Recursion, Greedy
677	Map Sum Pairs	Solution		Medium	HashMap
676	Implement Magic Dictionary	Solution		Medium
675	Cut Off Trees for Golf Event	Solution		Hard	BFS
674	Longest Continuous Increasing Subsequence	Solution		Easy
673	Number of Longest Increasing Subsequence	Solution		Medium	DP
672	Bulb Switcher II	Solution		Medium	Math
671	Second Minimum Node In a Binary Tree	Solution		Easy	Tree, DFS
670	Maximum Swap	Solution		Medium	String
669	Trim a Binary Search Tree	Solution		Easy	Tree, DFS
668	Kth Smallest Number in Multiplication Table	Solution		Hard	Binary Search
667	Beautiful Arrangement II	Solution		Medium	Array
666	Path Sum IV	Solution		Medium	Tree, DFS
665	Non-decreasing Array	Solution		Easy
664	Strange Printer	Solution		Hard	DP
663	Equal Tree Partition	Solution		Medium	Tree
662	Maximum Width of Binary Tree	Solution		Medium	BFS, DFS
661	Image Smoother	Solution		Easy	Array
660	Remove 9	Solution		Hard	Math
659	Split Array into Consecutive Subsequences	Solution		Medium	HashMap
658	Find K Closest Elements	Solution		Medium
657	Judge Route Circle	Solution		Easy
656	Coin Path	Solution		Hard	DP
655	Print Binary Tree	Solution		Medium	Recursion
654	Maximum Binary Tree	Solution		Medium	Tree
653	Two Sum IV - Input is a BST	Solution		Easy	Tree
652	Find Duplicate Subtrees	Solution		Medium	Tree
651	4 Keys Keyboard	Solution		Medium	DP
650	2 Keys Keyboard	Solution		Medium	DP
649	Dota2 Senate	Solution		Medium	Greedy
648	Replace Words	Solution		Medium	Trie
647	Palindromic Substrings	Solution		Medium	DP
646	Maximum Length of Pair Chain	Solution		Medium	DP, Greedy
645	Set Mismatch	Solution		Easy
644	Maximum Average Subarray II	Solution		Hard	Binary Search
643	Maximum Average Subarray I	Solution		Easy
642	Design Search Autocomplete System	Solution		Hard	Design
640	Solve the Equation	Solution		Medium
639	Decode Ways II	Solution		Hard	DP
638	Shopping Offers	Solution		Medium	DP, DFS
637	Average of Levels in Binary Tree	Solution		Easy
636	Exclusive Time of Functions	Solution		Medium	Stack
635	Design Log Storage System	Solution		Medium	Design
634	Find the Derangement of An Array	Solution		Medium	Math
633	Sum of Square Numbers	Solution		Easy	Binary Search
632	Smallest Range	Solution		Hard	Heap
631	Design Excel Sum Formula	Solution		Hard	Design, Topological Sort
630	Course Schedule III	Solution		Hard	Heap, Greedy
629	K Inverse Pairs Array	Solution		Hard	DP
628	Maximum Product of Three Numbers	Solution		Easy
625	Minimum Factorization	Solution		Medium
624	Maximum Distance in Arrays	Solution		Easy	Sort, Array
623	Add One Row to Tree	Solution		Medium	Tree
621	Task Scheduler	Solution		Medium	Greedy, Queue
617	Merge Two Binary Trees	Solution		Easy	Tree, Recursion
616	Add Bold Tag in String	Solution		Medium	String
611	Valid Triangle Number	Solution		Medium	Binary Search
609	Find Duplicate File in System	Solution		Medium	HashMap
606	Construct String from Binary Tree	Solution		Easy	Tree, Recursion
605	Can Place Flowers	Solution		Easy	Array
604	Design Compressed String Iterator	Solution		Easy	Design, String
600	Non-negative Integers without Consecutive Ones	Solution		Hard	Bit Manipulation, DP
599	Minimum Index Sum of Two Lists	Solution		Easy	HashMap
598	Range Addition II	Solution		Easy
594	Longest Harmonious Subsequence	Solution		Easy	Array, HashMap
593	Valid Square	Solution		Medium	Math
592	Fraction Addition and Subtraction	Solution		Medium	Math
591	Tag Validator	Solution		Hard	Stack, String
590	N-ary Tree Postorder Traversal	Solution		Easy	DFS, recursion
589	N-ary Tree Preorder Traversal	Solution		Easy	DFS, recursion
588	Design In-Memory File System	Solution		Hard	Trie, Design
587	Erect the Fence	Solution		Hard	Geometry
583	Delete Operation for Two Strings	Solution		Medium	DP
582	Kill Process	Solution		Medium	Stack
581	Shortest Unsorted Continuous Subarray	Solution		Easy	Array, Sort
576	Out of Boundary Paths	Solution		Hard	DP, DFS
575	Distribute Candies	Solution		Easy	Array
573	Squirrel Simulation	Solution		Medium	Math
572	Subtree of Another Tree	Solution		Easy	Tree
568	Maximum Vacation Days	Solution		Hard	DP
567	Permutation in String	Solution		Medium	Sliding Windows, Two Pointers
566	Reshape the Matrix	Solution		Easy
565	Array Nesting	Solution		Medium
563	Binary Tree Tilt	Solution		Easy	Tree Recursion
562	Longest Line of Consecutive One in Matrix	Solution		Medium	Matrix DP
561	Array Partition I	Solution		Easy	Array
560	Subarray Sum Equals K	Solution		Medium	Array, HashMap
559	Maximum Depth of N-ary Tree	Solution		Easy	DFS, recursion
557	Reverse Words in a String III	Solution		Easy	String
556	Next Greater Element III	Solution		Medium	String
555	Split Concatenated Strings	Solution		Medium	String
554	Brick Wall	Solution		Medium	HashMap
553	Optimal Division	Solution	O(n)	O(n)
552	Student Attendance Record II	Solution	O(n)	O(1)
551	Student Attendance Record I	Solution	O(n)	O(1)
549	Binary Tree Longest Consecutive Sequence II	Solution	O(n)	O(n)
548	Split Array with Equal Sum	Solution	O(n^2)	O(n)
547	Friend Circles	Solution	O(n^2)	O(n)
546	Remove Boxes	Solution	O(n^3)	O(n^3)
545	Boundary of Binary Tree	Solution	O(n)	O(n)
544	Output Contest Matches	Solution	O(n)	O(n)
543	Diameter of Binary Tree	Solution	O(n)	O(h)
542	01 Matrix	Solution	O(m*n)	O(n)
541	Reverse String II	Solution	O(n)	O(1)
540	Single Element in a Sorted Array	Solution	O(n)	O(1)
539	Minimum Time Difference	Solution	O(logn)	O(1)
538	Convert BST to Greater Tree	Solution	O(n)	O(h)
537	Complex Number Multiplication	Solution	O(1)	O(1)
536	Construct Binary Tree from String	Solution	O(n)	O(h)
535	Encode and Decode TinyURL	Solution	O(1)	O(n)
533	Lonely Pixel II	Solution	O(m*n)	O(m) (m is number of rows)
532	K-diff Pairs in an Array	Solution	O(n)	O(n)
531	Lonely Pixel I	Solution	O(m*n)	O(1)
530	Minimum Absolute Difference in BST	Solution	O(n)	O(n)
529	Minesweeper	Solution	O(m*n)	O(k)
527	Word Abbreviation	Solution	O(n^2)	O(n)
526	Beautiful Arrangement	Solution	O(n)	O(h)
525	Contiguous Array	Solution	O(n)	O(n)
524	Longest Word in Dictionary through Deleting	Solution	O(n)	O(n)
523	Continuous Subarray Sum	Solution	O(n)	O(1)
522	Longest Uncommon Subsequence II	Solution	O(x*n^2) (x is average length of strings)	O(1)
521	Longest Uncommon Subsequence I	Solution	O(max(x,y)) (x and y are length of strings)	O(1)
520	Detect Capital	Solution	O(n)	O(1)
517	Super Washing Machines	Solution
516	Longest Palindromic Subsequence	Solution	O(n^2)	O(n^2)
515	Find Largest Value in Each Tree Row	Solution	O(n)	O(k)
514	Freedom Trail	Solution	O(?)	O(?)
513	Find Bottom Left Tree Value	Solution	O(n)	O(k)
509	Fibonacci Number	Solution			📺
508	Most Frequent Subtree Sum	Solution	O(n)	O(n)
507	Perfect Number	Solution	O(sqrt(n))	O(1)
506	Relative Ranks	Solution	O(nlogn)	O(n)
505	The Maze II	Solution	O(m*n)	O(m*n)
504	Base 7	Solution	O(1)	O(1)
503	Next Greater Element II	Solution	O(n)	O(n)
502	IPO	Solution	O(nlogn)	O(n)
501	Find Mode in Binary Tree	Solution	O(n)	O(k)
500	Keyboard Row	Solution	O(n)	O(1)
499	The Maze III	Solution	O(m*n)	O(m*n)
496	Next Greater Element I	Solution	O(n*m)	O(1)
498	Diagonal Traverse	Solution	O(m*n)	O(1)
495	Teemo Attacking	Solution	O(n)	O(1)
494	Target Sum	Solution	O(2^n)	O(1)
493	Reverse Pairs	Solution	O(nlogn)	O(1)
492	Construct the Rectangle	Solution	O(n)	O(1)
491	Increasing Subsequences	Solution	O(n!)	O(n)
490	The Maze	Solution	O(m*n)	O(m*n)
488	Zuma Game	Solution	O(?)	O(?)
487	Max Consecutive Ones II	Solution	O(n)	O(n)
486	Predict the Winner	Solution	O(2^n)	O(n^2)
485	Max Consecutive Ones	Solution	O(n)	O(1)
484	Find Permutation	Solution	O(n)	O(1)
483	Smallest Good Base	Solution	O(logn)	O(1)
482	License Key Formatting	Solution	O(n)	O(n)
481	Magical String	Solution	O(?)	O(?)
480	Sliding Window Median	Solution	O(nlogk)	O(k)
479	Largest Palindrome Product	Solution	O(n)	O(1)
477	Total Hamming Distance	Solution	O(n)	O(1)
476	Number Complement	Solution	O(n)	O(1)
475	Heaters	Solution	max(O(nlogn), O(mlogn)) - m is the length of houses, n is the length of heaters	O(1)
474	Ones and Zeroes	Solution	O(n)	O(m*n)
473	Matchsticks to Square	Solution	O(n!)	O(n)
472	Concatenated Words	Solution	O(n^2)	O(n)
471	Encode String with Shortest Length	Solution	O(n^3)	O(n^2)
469	Convex Polygon	Solution	O(n)	O(1)
468	Validate IP Address	Solution	O(n)	O(1)
467	Unique Substrings in Wraparound String	Solution	O(n)	O(1)
466	Count The Repetitions	Solution	O(max(m,n))	O(1)
465	Optimal Account Balancing	Solution
464	Can I Win	Solution	O(2^n)	O(n)
463	Island Perimeter	Solution	O(m*n)	O(1)
462	Minimum Moves to Equal Array Elements II	Solution	O(nlogn)	O(1)
461	Hamming Distance	Solution	O(n)	O(1)
460	LFU Cache	Solution	O(1)	O(n)
459	Repeated Substring Pattern	Solution	O(n)	O(n)
458	Poor Pigs	Solution	O(1)	O(1)
457	Circular Array Loop	Solution	O(n)	O(1)
456	132 Pattern	Solution	O(n)	O(n)
455	Assign Cookies	Solution	O(n)	O(1)
454	4Sum II	Solution	O(n)	O(n)
453	Minimum Moves to Equal Array Elements	Solution	O(n)	O(1)
452	Minimum Number of Arrows to Burst Balloons	Solution	O(nlogn)	O(1)
451	Sort Characters By Frequency	Solution	O(nlogn)	O(n)
450	Delete Node in a BST	Solution	O(?)	O(?)
449	Serialize and Deserialize BST	Solution	O(n)	O(h)
448	Find All Numbers Disappeared in an Array	Solution	O(n)	O(1)
447	Number of Boomerangs	Solution	O(n^2)	O(n)
446	Arithmetic Slices II - Subsequence	Solution	O(n^2)	O(n^2)
445	Add Two Numbers II	Solution	O(max(m,n)	O(max(m,n))
444	Sequence Reconstruction	Solution	O(n)	O(n)
443	String Compression	Solution	O(n)	O(n)
442	Find All Duplicates in an Array	Solution	O(n)	O(1)
441	Arranging Coins	Solution	O(n)	O(1)
440	K-th Smallest in Lexicographical Order	Solution	O(n^2)	O(1)
439	Ternary Expression Parser	Solution	O(n)	O(n)
438	Find All Anagrams in a String	Solution	O(n)	O(1)
437	Path Sum III	Solution	O(n^2)	O(n)
436	Find Right Interval	Solution	O(nlogn)	O(n)
435	Non-overlapping Intervals	Solution	O(nlogn)	O(1)
434	Number of Segments in a String	Solution	O(n)	O(1)
432	All O`one Data Structure	Solution	O(1)	O(n)
429	N-ary Tree Level Order Traversal	Solution	O(n)	O(n)
425	Word Squares	Solution	O(n!)	O(n)
424	Longest Repeating Character Replacement	Solution	O(n)	O(1)
423	Reconstruct Original Digits from English	Solution	O(n)	O(1)
422	Valid Word Square	Solution	O(n)	O(1)
421	Maximum XOR of Two Numbers in an Array	Solution	O(n)	O(1)
420	Strong Password Checker	Solution	?	?
419	Battleships in a Board	Solution	O(m*n)	O(1)
418	Sentence Screen Fitting	Solution	O(n)	O(1)
417	Pacific Atlantic Water Flow	Solution	O(mnMax(m,n))	O(m*n)
416	Partition Equal Subset Sum	Solution	O(m*n)	O(m*n)
415	Add Strings	Solution	O(n)	O(1)
414	Third Maximum Number	Solution	O(n)	O(1)
413	Arithmetic Slices	Solution	O(n)	O(1)
412	Fizz Buzz	Solution	O(n)	O(1)
411	Minimum Unique Word Abbreviation	Solution	O(?)	O(?)
410	Split Array Largest Sum	Solution	O(nlogn)	O(1)
409	Longest Palindrome	Solution	O(n)	O(1)
408	Valid Word Abbreviation	Solution	O(n)	O(1)
407	Trapping Rain Water II	Solution
406	Queue Reconstruction by Height	Solution	O(nlogn)	O(1)
405	Convert a Number to Hexadecimal	Solution	O(n)	O(1)
404	Sum of Left Leaves	Solution	O(n)	O(h)
403	Frog Jump	Solution	O(n^2)	O(n^2)
402	Remove K Digits	Solution	O(n)	O(n)
401	Binary Watch	Solution	O(1)	O(1)
400	Nth Digit	Solution	O(n)	O(1)
399	Evaluate Division	Solution	O(n*n!)	O(n)
398	Random Pick Index	Solution
397	Integer Replacement	Solution	?	?
396	Rotate Function	Solution	O(n^2) could be optimized to O(n)	O(1)
395	Longest Substring with At Least K Repeating Characters	Solution	O(n^2)	O(1)
394	Decode String	Solution	O(n)	O(n)
393	UTF-8 Validation	Solution	O(?)	O(?)
392	Is Subsequence	Solution	O(m*n)	O(1)
391	Perfect Rectangle	Solution	O(n)	O(1)
390	Elimination Game	Solution	O(logn)	O(1)
389	Find the Difference	Solution	O(n)	O(1)
388	Longest Absolute File Path	Solution	O(n)	O(d)
387	First Unique Character in a String	Solution	O(n)	O(n)
386	Lexicographical Numbers	Solution	O(n)	O(1)
385	Mini Parser	Solution	O(n)	O(h)
384	Shuffle an Array	Solution	O(n)	O(n)
383	Ransom Note	Solution	O(n)	O(n)
382	Linked List Random Node	Solution	O(1)	O(n)
381	Insert Delete GetRandom O(1) - Duplicates allowed	Solution
380	Insert Delete GetRandom O(1)	Solution	O(n)	O(1)
379	Design Phone Directory	Solution	O(1)	O(n)
378	Kth Smallest Element in a Sorted Matrix	Solution	O(logm*n)	O(1)
377	Combination Sum IV	Solution	O(n^2)	O(n)
376	Wiggle Subsequence	Solution	O(n)	O(1)
375	Guess Number Higher or Lower II	Solution	O(n^2)	O(n^2)
374	Guess Number Higher or Lower	Solution	O(logn)	O(1)
373	Find K Pairs with Smallest Sums	Solution	O(klogk)	O(k)
372	Super Pow	Solution	O(n)	O(1)
371	Sum of Two Integers	Solution	O(n)	O(1)
370	Range Addition	Solution	O(n+k)	O(1)
369	Plus One Linked List	Solution	O(n)	O(1)
368	Largest Divisible Subset	Solution	O(n^2)	O(n)
367	Valid Perfect Square	Solution	O(n)	O(1)
366	Find Leaves of Binary Tree	Solution	O(n)	O(h)
365	Water and Jug Problem	Solution	O(n)	O(1)
364	Nested List Weight Sum II	Solution	O(n)	O(h)
363	Max Sum of Rectangle No Larger Than K	Solution
362	Design Hit Counter	Solution	O(1) amortized	O(k)
361	Bomb Enemy	Solution	O(?)	O(?)
360	Sort Transformed Array	Solution	O(n)	O(1)
359	Logger Rate Limiter	Solution	amortized O(1)	O(k)
358	Rearrange String k Distance Apart	Solution	O(n)	O(n)
357	Count Numbers with Unique Digits	Solution	O(n)	O(1)
356	Line Reflection	Solution	O(n)	O(n)
355	Design Twitter	Solution	O(n)	O(n)
354	Russian Doll Envelopes	Solution	O(nlogn)	O(1)
353	Design Snake Game	Solution	O(?)	O(?)
352	Data Stream as Disjoint Intervals	Solution	O(logn)	O(n)
351	Android Unlock Patterns	Solution	O(?)	O(?)
350	Intersection of Two Arrays II	Solution	O(m+n)	O((m+n)) could be optimized
349	Intersection of Two Arrays	Solution	O(m+n)	O(min(m,n))
348	Design Tic-Tac-Toe	Solution	O(1)	O(n)
347	Top K Frequent Elements	Solution	O(n)	O(k) k is is the number of unique elements in the given array
346	Moving Average from Data Stream	Solution	O(1)	O(w))
345	Reverse Vowels of a String	Solution	O(n)	O(1)
344	Reverse String	Solution	O(n)	O(1)
343	Integer Break	Solution	O(1)	O(1)
342	Power of Four	Solution	O(n)	O(1)
341	Flatten Nested List Iterator	Solution	O(n)	O(n)
340	Longest Substring with At Most K Distinct Characters	Solution	O(n)	O(1)
339	Nested List Weight Sum	Solution	O(n)	O(h))
338	Counting Bits	Solution	O(nlogn)	O(h)
337	House Robber III	Solution	O(n)	O(n)
336	Palindrome Pairs	Solution	O(n^2)	O(n)
335	Self Crossing	Solution	O(n)	O(1)
334	Increasing Triplet Subsequence	Solution	O(n)	O(1)
333	Largest BST Subtree	Solution	O(n)	O(n)
332	Reconstruct Itinerary	Solution	O(n)	O(n)
331	Verify Preorder Serialization of a Binary Tree	Solution	O(n)	O(n)
330	Patching Array	Solution	O(m+logn)	O(1)
329	Longest Increasing Path in a Matrix	Solution	O(m*n)	O(m*n)
328	Odd Even Linked List	Solution	O(n)	O(1)
327	Count of Range Sum	Solution	O(nlogn)	O(n)
326	Power of Three	Solution	O(1)	O(1)
325	Maximum Size Subarray Sum Equals k	Solution	O(n)	O(n)
324	Wiggle Sort II	Solution	O(n)	O(n)
323	Number of Connected Components in an Undirected Graph	Solution	O(?)	O(?)
322	Coin Change	Solution	O(n*k)	O(k)
321	Create Maximum Number	Solution	O(?)	O(?)
320	Generalized Abbreviation	Solution	O(n*2^n)	O(n)
319	Bulb Switcher	Solution	O(1)	O(1)
318	Maximum Product of Word Lengths	Solution	O(n^2)	O(n)
317	Shortest Distance from All Buildings	Solution	O(?)	O(?)
316	Remove Duplicate Letters	Solution	O(n)	O(1)
315	Count of Smaller Numbers After Self	Solution	O(?)	O(?)
314	Binary Tree Vertical Order Traversal	Solution	O(n)	O(n)
313	Super Ugly Number	Solution	O(?)	O(?)
312	Burst Balloons	Solution	O(?)	O(?)
311	Sparse Matrix Multiplication	Solution	O(mnl)	O(m*l)
310	Minimum Height Trees	Solution	?	?
309	Best Time to Buy and Sell Stock with Cooldown	Solution	O(n)	O(1)
308	Range Sum Query 2D - Mutable	Solution	?	?
307	Range Sum Query - Mutable	Solution	?	?
306	Additive Number	Solution	O(n^2)	O(n)
305	Number of Islands II	Solution	?	?
304	Range Sum Query 2D - Immutable	Solution	?	?
303	Range Sum Query - Immutable	Solution	O(n)	O(1)
302	Smallest Rectangle Enclosing Black Pixels	Solution	?	O(m*n)
301	Remove Invalid Parentheses	Solution	?	?
300	Longest Increasing Subsequence	Solution	O(logn)	O(n)
299	Bulls and Cows	Solution	O(n)	O(1)
298	Binary Tree Longest Consecutive Sequence	Solution	O(n)	O(n)
297	Serialize and Deserialize Binary Tree	Solution	O(n)	O(h)
296	Best Meeting Point	Solution	?	?
295	Find Median from Data Stream	Solution	O(logn)	O(n)
294	Flip Game II	Solution	O(?)	O(?)
293	Flip Game	Solution	O(n)	O(1)
292	Nim Game	Solution	O(1)	O(1)
291	Word Pattern II	Solution	O(n)	O(n)
290	Word Pattern	Solution	O(n)	O(n)
289	Game of Life	Solution	O(m*n)	O(m*n), could be optimized to O(1)
288	Unique Word Abbreviation	Solution	O(n)	O(1)
287	Find the Duplicate Number	Solution	O(n)	O(1)
286	Walls and Gates	Solution	O(m*n)	O(g)
285	Inorder Successor In BST	Solution	O(h)	O(1)
284	Peeking Iterator	Solution	O(n)	O(n)
283	Move Zeroes	Solution	O(n)	O(1)
282	Expression Add Operators	Solution	O(?)	O(?)
281	Zigzag Iterator	Solution	O(1)	O(k)
280	Wiggle Sort	Solution	O(n)	O(1)
279	Perfect Squares	Solution	O(n)	O(1)
278	First Bad Version	Solution	O(logn)	O(1)
277	Find the Celebrity	Solution	O(n)	O(1)
276	Paint Fence	Solution	O(n)	O(1)
275	H-Index II	Solution	O(logn)	O(1)
274	H-Index	Solution	O(nlogn)	O(1)
273	Integer to English Words	Solution	O(n)	O(1)
272	Closest Binary Search Tree Value II	Solution	O(h+k)	O(h)
271	Encode and Decode Strings	Solution	O(n)	O(1)
270	Closest Binary Search Tree Value	Solution	O(h)	O(1)
269	Alien Dictionary	Solution	O(?)	O(?)
268	Missing Number	Solution	O(n)	O(1)
267	Palindrome Permutation II	Solution	O(n*n!)	O(n)
266	Palindrome Permutation	Solution	O(n)	O(1)
265	Paint House II	Solution	O(n*k)	O(1)
264	Ugly Number II	Solution	O(n)	O(n)
263	Ugly Number	Solution	O(n)	O(1)
261	Graph Valid Tree	Solution	O(V+E)	O(V+E)
260	Single Number III	Solution	O(n)	O(n)
259	3Sum Smaller	Solution	O(n^2)	O(1)
258	Add Digits	Solution	O(1)	O(1)
257	Binary Tree Paths	Solution	O(n*h)	O(h)
256	Paint House	Solution	O(n)	O(1)
255	Verify Preorder Sequence in Binary Search Tree	Solution	O(n)	O(h)
254	Factor Combinations	Solution	O(nlogn)	O(nlogn)
253	Meeting Rooms II	Solution	O(nlogn)	O(h)
252	Meeting Rooms	Solution	O(nlogn)	O(1)
251	Flatten 2D Vector	Solution	O(1)	O(m*n)
250	Count Univalue Subtrees	Solution	O(n)	O(h)
249	Group Shifted Strings	Solution	O(nlogn)	O(n)
248	Strobogrammatic Number III	Solution	O(?)	O(?)
247	Strobogrammatic Number II	Solution	O(n^2)	O(n)
246	Strobogrammatic Number	Solution	O(n)	O(1)
245	Shortest Word Distance III	Solution	O(n)	O(1)
244	Shortest Word Distance II	Solution	O(n)	O(n)
243	Shortest Word Distance	Solution	O(n)	O(1)
242	Valid Anagram	Solution	O(n)	O(1)
241	Different Ways to Add Parentheses	Solution	O(O(n * 4^n / n^(3/2)))	O(n * 4^n / n^(3/2))
240	Search a 2D Matrix II	Solution	O(m+n)	O(1)
239	Sliding Window Maximum	Solution	O(nlogn)	O(k)
238	Product of Array Except Self	Solution	O(n)	O(1)
237	Delete Node in a Linked List	Solution	O(1)	O(1)
236	Lowest Common Ancestor of a Binary Tree	Solution	O(n)	O(h)
235	Lowest Common Ancestor of a Binary Search Tree	Solution	O(h)	O(1)
234	Palindrome Linked List	Solution	O(n)	O(1)
233	Number of Digit One	Solution	O(n)	O(1)
232	Implement Queue using Stacks	Solution	O(n)	O(n)
231	Power of Two	Solution	O(1)	O(1)
230	Kth Smallest Element in a BST	Solution	O(n)	O(k)
229	Majority Element II	Solution	O(n)	O(1)
228	Summary Ranges	Solution	O(n)	O(1)
227	Basic Calculator II	Solution	O(n)	O(n)
226	Invert Binary Tree	Solution	O(n)	O(h)
225	Implement Stack using Queues	Solution	O(n)	O(n)
224	Basic Calculator	Solution	?	?
223	Rectangle Area	Solution	O(1)	O(1)
222	Count Complete Tree Nodes	Solution	O(?)	O(h)
221	Maximal Square	Solution	O(?)	O(h)
220	Contains Duplicate III	Solution	O(nlogn)	O(n)
219	Contains Duplicate II	Solution	O(n)	O(n)
218	The Skyline Problem	Solution	O(n)	O(n)
217	Contains Duplicate	Solution	O(n)	O(n)
216	Combination Sum III	Solution	O(k * C(n, k))	O(k)
215	Kth Largest Element in an Array	Solution	O(nlogn)	O(n)
214	Shortest Palindrome	Solution	O(?)	O(?)
213	House Robber II	Solution	O(n)	O(n)
212	Word Search II	Solution	O(mnl)	O(l)
211	Add and Search Word - Data structure design	Solution	O(n)	O(h)
210	Course Schedule II	Solution	O(?)	O(?)
209	Minimum Size Subarray Sum	Solution	O(n)	O(1)
208	Implement Trie	Solution	O(n)	O(1)
207	Course Schedule	Solution	O(?)	O(?)
206	Reverse Linked List	Solution	O(n)	O(1)
205	Isomorphic Strings	Solution	O(n)	O(1)
204	Count Primes	Solution	O(nloglogn)	O(n)
203	Remove Linked List Elements	Solution	O(n)	O(1)
202	Happy Number	Solution	O(k)	O(k)
201	Bitwise AND of Numbers Range	Solution	O(min(m,n))	O(1)
200	Number of Islands	Solution	O(m*n)	O(m*n)
199	Binary Tree Right Side View	Solution	O(n)	O(h)
198	House Robber	Solution	O(n)	O(n)
191	Number of 1 Bits	Solution	O(1)	O(1)
190	Reverse Bits	Solution	O(n)	O(1)
189	Rotate Array	Solution	O(n)	O(n), could be optimized to O(1)
188	Best Time to Buy and Sell Stock IV	Solution	O(n*k)	O(n*k)
187	Repeated DNA Sequences	Solution	O(n)	O(n)
186	Reverse Words in a String II	Solution	O(n)	O(1)
179	Largest Number	Solution	O(?)	O(?)
174	Dungeon Game	Solution	O(m*n)	O(m*n)
173	Binary Search Tree Iterator	Solution	O(1)	O(h)
172	Factorial Trailing Zeroes	Solution	O(logn)	O(1)
171	Excel Sheet Column Number	Solution	O(n)	O(1)
170	Two Sum III - Data structure design	Solution	O(n)	O(n)
169	Majority Element	Solution	O(n)	O(1)
168	Excel Sheet Column Title	Solution	O(n)	O(1)
167	Two Sum II - Input array is sorted	Solution	O(n)	O(1)
166	Fraction to Recurring Decimal	Solution	O(1)	O(1)
165	Compare Version Numbers	Solution	O(n)	O(1)
164	Maximum Gap	Solution	O(n)	O(n)
163	Missing Ranges	Solution	O(n)	O(1)
162	Find Peak Element	Solution	O(1)	O(logn)/O(n)
161	One Edit Distance	Solution	O(n)	O(1)
160	Intersection of Two Linked Lists	Solution	O(m+n)	O(1)
159	Longest Substring with At Most Two Distinct Characters	Solution	O(n)	O(1)
158	Read N Characters Given Read4 II - Call multiple times	Solution	O(n)	O(1)
157	Read N Characters Given Read4	Solution	O(n)	O(1)
156	Binary Tree Upside Down	Solution	O(n)	O(h)
155	Min Stack	Solution	O(1)	O(n)
154	Find Minimum in Rotated Sorted Array II	Solution	O(logn)	O(1)
153	Find Minimum in Rotated Sorted Array	Solution	O(logn)	O(1)
152	Maximum Product Subarray	Solution	O(n)	O(1)
151	Reverse Words in a String	Solution	O(n)	O(n)
150	Evaluate Reverse Polish Notation	Solution	O(?)	O(?)
149	Max Points on a Line	Solution	O(?)	O(?)
148	Sort List	Solution	O(nlogn)	O(h)
147	Insertion Sort List	Solution	O(n^2)	O(1)
146	LRU Cache	Solution	amortized O(1)	O(k)
145	Binary Tree Postorder Traversal	Solution	O(n)	O(h)
144	Binary Tree Preorder Traversal	Solution	O(n)	O(h)
143	Reorder List	Solution	O(n)	O(1)
142	Linked List Cycle II	Solution	O(n)	O(1)
141	Linked List Cycle	Solution	O(n)	O(1)
140	Word Break II	Solution	?	O(n^2)
139	Word Break	Solution	O(n^2)	O(n)
138	Copy List with Random Pointer	Solution	O(n)	O(n)
137	Single Number II	Solution	O(n)	O(1)
136	Single Number	Solution	O(n)	O(1)
135	Candy	Solution	O(n)	O(1)
134	Gas Station	Solution	O(n)	O(1)
133	Clone Graph	Solution	O(n)	O(n)
132	Palindrome Partitioning II	Solution	O(n^2)	O(n^2)
131	Palindrome Partitioning	Solution	O(n^2)	O(n^2)
130	Surrounded Regions	Solution	O(?)	O(?)
129	Sum Root to Leaf Numbers	Solution	O(n)	O(h)
128	Longest Consecutive Sequence	Solution	O(n)	O(n)
127	Word Ladder	Solution	O(n^2)	O(n)
126	Word Ladder II	Solution	O(?)	O(?)
125	Valid Palindrome	Solution	O(n)	O(1)
124	Binary Tree Maximum Path Sum	Solution	O(n)	O(h)
123	Best Time to Buy and Sell Stock III	Solution	O(n)	O(1)
122	Best Time to Buy and Sell Stock II	Solution	O(n)	O(1)
121	Best Time to Buy and Sell Stock	Solution	O(n)	O(1)
120	Triangle	Solution	O(m*n)	O(n)
119	Pascal's Triangle II	Solution	O(n^2)	O(k)	📺
118	Pascal's Triangle	Solution	O(n^2)	O(1)
117	Populating Next Right Pointers in Each Node II	Solution	O(n)	O(1)
116	Populating Next Right Pointers in Each Node	Solution	O(n)	O(1)
115	Distinct Subsequences	Solution	O(m*n)	O(m*n)
114	Flatten Binary Tree to Linked List	Solution	O(n)	O(h)
113	Path Sum II	Solution	O(n)	O(h)
112	Path Sum	Solution	O(n)	O(1)
111	Minimum Depth of Binary Tree	Solution	O(n)	O(1)~O(h)
110	Balanced Binary Tree	Solution	O(n)	O(1)~O(h)
109	Convert Sorted List to Binary Search Tree	Solution	O(n)	O(h)
108	Convert Sorted Array to Binary Search Tree	Solution	O(n)	O(h)
107	Binary Tree Level Order Traversal II	Solution	O(nlogn)	O(h)
106	Construct Binary Tree from Inorder and Postorder Traversal	Solution	O(n)	O(n)
105	Construct Binary Tree from Preorder and Inorder Traversal	Solution	O(n)	O(n)
104	Maximum Depth of Binary Tree	Solution	O(n)	O(h)
103	Binary Tree Zigzag Level Order Traversal	Solution	O(n)	O(h)
102	Binary Tree Level Order Traversal	Solution	O(n)	O(h)
101	Symmetric Tree	Solution	O(n)	O(h)	📺
100	Same Tree	Solution	O(n)	O(h)	📺
99	Recover Binary Search Tree	Solution	O(?)	O(?)
98	Validate Binary Search Tree	Solution	O(n)	O(h)
97	Interleaving String	Solution	O(?)	O(?)
96	Unique Binary Search Trees	Solution	O(n^2)	O(n)
95	Unique Binary Search Trees II	Solution	O(?)	O(?)
94	Binary Tree Inorder Traversal	Solution	O(n)	O(h)
93	Restore IP Addresses	Solution	O(?)	O(?)
92	Reverse Linked List II	Solution	O(n)	O(1)
91	Decode Ways	Solution	O(n)	O(n)
90	Subsets II	Solution	O(n^2)	O(1)
89	Gray Code	Solution	O(n)	O(1)
88	Merge Sorted Array	Solution	O(max(m,n))	O(1)
87	Scramble String	Solution	O(n^4)	O(n^3
86	Partition List	Solution	O(n)	O(1)
85	Maximal Rectangle	Solution	O(m*n)	O(n)
84	Largest Rectangle in Histogram	Solution	O(n)	O(n)
83	Remove Duplicates from Sorted List	Solution	O(n)	O(1)
82	Remove Duplicates from Sorted List II	Solution	O(n)	O(1)
81	Search in Rotated Sorted Array II	Solution	O(logn)	O(1)
80	Remove Duplicates from Sorted Array II	Solution	O(n)	O(n)
79	Word Search	Solution	O((m*n)^2)	O(m*n)
78	Subsets	Solution	O(n^2)	O(1)
77	Combinations	Solution	O(n!)	O(n)
76	Minimum Window Substring	Solution	O(n)	O(k)
75	Sort Colors	Solution	O(n)	O(1)
74	Search a 2D Matrix	Solution	O(log(m*n))	O(1)
73	Set Matrix Zeroes	Solution	O(mn)	O(1)
72	Edit Distance	Solution	O(m*n)	O(m+n)
71	Simplify Path	Solution	O(n)	O(n)
70	Climbing Stairs	Solution	O(n)	O(n)
69	Sqrt(x)	Solution	O(logn)	O(1)
68	Text Justification	Solution	O(n)	O(1)
67	Add Binary	Solution	O(n)	O(1)
66	Plus One	Solution	O(n)	O(1)
65	Valid Number	Solution	O(n)	O(1)
64	Minimum Path Sum	Solution	O(m*n)	O(m*n)
63	Unique Paths II	Solution	O(m*n)	O(m*n)
62	Unique Paths	Solution	O(m*n)	O(m*n)
61	Rotate List	Solution	O(n)	O(1)
60	Permutation Sequence	Solution	O(n^2)	O(n)
59	Spiral Matrix II	Solution	O(n)	O(n)
58	Length of Last Word	Solution	O(n)	O(1)
57	Insert Intervals	Solution	O(n)	O(1)
56	Merge Intervals	Solution	O(n*logn)	O(1)
55	Jump Game	Solution	O(n)	O(1)
54	Spiral Matrix	Solution	O(m*n)	O(m*n)
53	Maximum Subarray	Solution	O(n)	O(1)
52	N-Queens II	Solution	O(n!)	O(n)
51	N-Queens	Solution	O(n!)	O(n)
50	Pow(x, n)	Solution	O(logn)	O(logn)
49	Group Anagrams	Solution	O(m*klogk)	O(m*k)
48	Rotate Image	Solution	O(n^2)	O(1)
47	Permutations II	Solution	O(n*n!)	O(n)
46	Permutations	Solution	O(n*n!)	O(n)
45	Jump Game II	Solution	O(n)	O(1)
44	Wildcard Matching	Solution	O(m*n)	O(m*n)
43	Multiply Strings	Solution	O(n)	O(1)
42	Trapping Rain Water	Solution	O(n)	O(1)
41	First Missing Positive	Solution	O(n)	O(1)
40	Combination Sum II	Solution	O(k*n^k)	O(k)
39	Combination Sum	Solution	O(k*n^k)	O(k)
38	Count and Say	Solution	O(n*2^n)	O(2^n)
37	Sudoku Solver	Solution	O((9!)^9)	O(1)
36	Valid Sudoku	Solution	O(1)	O(1)
35	Search Insert Position	Solution	O(n)	O(1)
34	Search for a Range	Solution	O(logn)	O(1)
33	Search in Rotated Sorted Array	Solution	O(logn)	O(1)
32	Longest Valid Parentheses	Solution	O(n)	O(n)
31	Next Permutation	Solution	O(n)	O(1)
30	Substring with Concatenation of All Words	Solution	O(n^2)	O(n)
29	Divide Two Integers	Solution	O(?)	O(?)
28	Implement strStr()	Solution	O(n)	O(1)
27	Remove Element	Solution	O(n)	O(1)
26	Remove Duplicates from Sorted Array	Solution	O(n)	O(1)
25	Reverse Nodes in k-Group	Solution	O(n)	O(1)
24	Swap Nodes in Pairs	Solution	O(n)	O(h)
23	Merge k Sorted Lists	Solution	O(n*logk)	O(k)	📺
22	Generate Parentheses	Solution	TBD	O(n)
21	Merge Two Sorted Lists	Solution	O(n)	O(h)
20	Valid Parentheses	Solution	O(n)	O(n)	📺
19	Remove Nth Node From End of List	Solution	O(n)	O(1)
18	4 Sum	Solution	O(n^2)	O(1)
17	Letter Combinations of a Phone Number	Solution	O(n*4^n)	O(n)
16	3Sum Closest	Solution	O(nlogn)	O(1)
15	3Sum	Solution	O(n^2)	O(1)	📺
14	Longest Common Prefix	Solution	O(S) (S is the sum of all characters in all strings)	O(1)	📺
13	Roman to Integer	Solution	O(1)	O(1)
12	Integer to Roman	Solution	O(1)	O(1)
11	Container With Most Water	Solution	O(n)	O(1)
10	Regular Expression Matching	Solution	O(m*n)	O(m*n)
9	Palindrome Number	Java, C++	O(n)	O(1)
8	String to Integer (atoi)	Solution	O(n)	O(1)
7	Reverse Integer	Solution	O(1)	O(1)
6	ZigZag Conversion	Solution	O(n)	O(n)
5	Longest Palindromic Substring	Solution	O(n^2)	O(1)
4	Median of Two Sorted Arrays	Solution	?	?
3	Longest Substring Without Repeating Characters	Solution	O(n)	O(k)
2	Add Two Numbers	Solution	O(max(m,n))	O(1)
1	Two Sum	Java, C++	O(n)	O(n)	📺

Database

#	Title	Solutions	Time	Space	Difficulty	Tag
1280	Students and Examinations	Solution		📺	Easy
1251	Average Selling Price	Solution			Easy
1179	Reformat Department Table	Solution			Easy
1069	Product Sales Analysis II	Solution			Easy
1068	Product Sales Analysis I	Solution			Easy
627	Swap Salary	Solution			Easy
626	Exchange Seats	Solution			Medium
620	Not Boring Movies	Solution			Easy
619	Biggest Single Number	Solution			Easy
618	Students Report By Geography	Solution			Hard	Session Variables
615	Average Salary: Departments VS Company	Solution			Hard
614	Second Degree Follower	Solution			Medium	Inner Join
613	Shortest Distance in a Line	Solution			Easy
612	Shortest Distance in a Plane	Solution			Medium
610	Triangle Judgement	Solution			Easy
608	Tree Node	Solution			Medium	Union
607	Sales Person	Solution			Easy
603	Consecutive Available Seats	Solution			Easy
602	Friend Requests II: Who Has the Most Friends	Solution			Medium
601	Human Traffic of Stadium	Solution			Hard
597	Friend Requests I: Overall Acceptance Rate	Solution			Easy
596	Classes More Than 5 Students	Solution			Easy
595	Big Countries	Solution	O(n)	O(1)	Easy
586	Customer Placing the Largest Number of Orders	Solution			Easy
585	Investments in 2016	Solution			Medium
584	Find Customer Referee	Solution			Easy
580	Count Student Number in Departments	Solution			Medium	Left Join
578	Get Highest Answer Rate Question	Solution			Medium
577	Employee Bonus	Solution			Easy
574	Winning Candidate	Solution			Medium
571	Find Median Given Frequency of Numbers	Solution			Hard
570	Managers with at Least 5 Direct Reports	Solution			Medium
569	Median Employee Salary	Solution			Hard
511	Game Play Analysis I	Solution			Easy
262	Trips and Users	Solution			Hard	Inner Join
197	Rising Temperature	Solution	O(n^2)	O(n)	Easy
196	Delete Duplicate Emails	Solution	O(n^2)	O(n)	Easy
185	Department Top Three Salaries	Solution			Hard
184	Department Highest Salary	Solution	O(n^2)	O(n)	Medium
183	Customers Who Never Order	Solution	O(n^2)	O(n)	Easy
182	Duplicate Emails	Solution	O(n^2)	O(n)	Easy
181	Employees Earning More Than Their Managers	Solution	O(n^2)	O(n)	Easy
180	Consecutive Numbers	Solution	O(n)	O(n)	Medium
178	Rank Scores	Solution	?	?	Medium
177	Nth Highest Salary	Solution	O(n)	O(1)	Medium
176	Second Highest Salary	Solution	O(n)	O(1)	Easy
175	Combine Two Tables	Solution	O(m+n)	O(m+n)	Easy

Shell

#	Title	Solutions	Time	Space	Difficulty	Tag
195	Tenth Line	Solution	O(n)	O(1)	Easy
194	Transpose File	Solution	O(n^2)	O(n^2)	Medium
193	Valid Phone Numbers	Solution	O(n)	O(1)	Easy
192	Word Frequency	Solution	O(n)	O(k)	Medium

Contributing

Your ideas/fixes/algorithms are more than welcome!

1. Fork this repo
2. Clone your forked repo (git clone https://github.com/YOUR_GITHUB_USERNAME/Leetcode.git) onto your local machine
3. cd into your cloned directory, create your feature branch (git checkout -b my-awesome-fix)
4. git add your desired changes to this repo
5. Commit your changes (git commit -m 'Added some awesome features/fixes')
6. Push to the branch (git push origin my-awesome-feature)
7. Open your forked repo on Github website, create a new Pull Request to this repo!

Best way to open this project

1. Install Intellij on your machine, either CE or UE.
2. git clone this repo to your local disk
3. import this project as a new project (does need to be imported as a gradle project)
4. If you run into "Could not determine Java version using executable ..." error, use local gradle distribution: "/usr/local/Cellar/gradle/4.8.1/libexec/" instead of the default one. More details, see Stackoverflow.