Online Judges

This repository contains my solutions to problems in different online judge platforms such as LeetCode, Work@Tech, etc. If you like this repository, consider giving it a star ⭐.

Connect with me via

• 1. LeetCode
• 2. Work At Tech

LeetCode

#	Title	Solutions	Difficulty	Tag
2869	Minimum Operations To Collect Elements	Solution	Easy	Array
2439	Minimize Maximum Of Array	Solution	Medium	Array, Greedy, Prefix Sum
2405	Optimal Partitioning Of String	Solution	Medium	String, Hash Table
2390	Removing Stars From A String	Solution	Medium	Stack, Simulation
2349	Design A Number Container System	Solution	Medium	Design, Hash Set
2336	Smallest Number In Infinite Set	Solution	Medium	Design, Heap, Hash Set
2305	Fair Distribution Of Cookies	Solution	Medium	Backtracking
2300	Successful Pairs Of Spells And Potions	Solution	Medium	Array, Binary Search
2265	Count Nodes Equal To Average Of Subtree	Solution	Medium	Tree
2236	Root Equals Sum Of Children	Solution	Easy	Tree
2235	Add Two Integers	Solution	Easy	Math
2218	Maximum Value Of K Coins From Piles	Solution	Hard	Dynamic Programming
2215	Find The Difference Of Two Arrays	Solution	Easy	Array, Hash Table
2167	Count Operations To Obtain Zero	Solution	Easy	Math
2164	Sort Even And Odd Indices Independently	Solution	Easy	Heap, Sorting
2140	Solving Questions With Brainpower	Solution	Medium	Dynamic Programming
2022	Convert 1D Array Into 2D Array	Solution	Easy	Array, Matrix
2011	Final Value Of Variable After Performing Operations	Solution	Easy	String
1964	Find The Longest Valid Obstacle Course At Each Position	Solution	Hard	Array, Greedy, Binary Search
1929	Concatenation Of Array	Solution	Easy	Array
1928	Minimum Cost To Reach Destination In Time	Solution	Hard	Graph, Dijkstra
1921	Eliminate Maximum Number Of Monsters	Solution	Medium	Array, Greedy
1920	Build Array From Permutation	Solution	Easy	Array
1913	Maximum Product Difference Between Two Pairs	Solution	Easy	Array, Sort
1857	Largest Color Value In A Directed Graph	Solution	Hard	Graph, Topological Sort
1845	Seat Reservation Manager	Solution	Medium	Heap
1822	Sign Of The Product Of An Array	Solution	Easy	Math
1768	Merge Strings Alternately	Solution	Easy	String, Two Pointers
1757	Recyclable And Low Fat Products	Solution	Easy	Database
1721	Swapping Noes In A Linked List	Solution	Medium	Linked List
1697	Checking Existence Of Edge Length Limited Paths	Solution	Hard	Union Find, Graph
1695	Maximum Erasure Value	Solution	Medium	Array, Two Pointers
1689	Partitioning Into Minimum Number Of Deci-Binary Numbers	Solution	Medium	String, Greedy
1679	Max Number Of K-Sum Pairs	Solution	Medium	Array
1675	Minimize Deviation In Array	Solution	Hard	Heap
1672	Richest Customer Wealth	Solution	Easy	Array, Matrix
1663	Smallest String With A Given Numeric Value	Solution	Medium	String, Greedy
1658	Minimum Operations To Reduce X To Zero	Solution	Medium	Array, Sliding Window
1647	Minimum Deletions To Make Character Frequencies Unique	Solution	Medium	Heap
1642	Furthest Building You Can Reach	Solution	Medium	Heap
1641	Count Sorted Vowel Strings	Solution	Medium	Math
1639	Number Of Ways To Form A Target String Given A Dictionary	Solution	Medium	Dynamic Programming
1631	Path With Minimum Effort	Solution	Medium	Array, DFS
1584	Min Cost To Connect All Points	Solution	Medium	Graph, Minimum Spanning Tree
1579	Remove Max Number Of Edges To Keep Graph Fully Traversable	Solution	Hard	Union Find, Graph
1572	Matrix Diagonal Sum	Solution	Easy	Array, Matrix
1567	Maximum Length Of Subarray With Positive Product	Solution	Medium	Dynamic Programming, Array
1535	Find The Winner Of An Array Game	Solution	Medium	Array, Simulation
1510	Stone Game IV	Solution	Hard	Dynamic Programming, Array
1503	Last Moment Before All Ants Fall Out Of A Plank	Solution	Medium	Array, Simulation
1498	Number Of Subsequences That Satisfy The Given Sum Condition	Solution	Medium	Array, Two Pointers, Binary Search
1491	Average Salary Excluding The Minimum And Maximum Salary	Solution	Easy	Array
1480	Running Sum Of 1D Array	Solution	Easy	Array, Prefix Sum
1463	Cherry Pickup II	Solution	Hard	Dynamic Programming
1461	Check If A String Contains All Binary Codes Of Size K	Solution	Medium	String
1456	Maximum Number Of Vowels In A Substring Of Given Length	Solution	Medium	String, Sliding Window
1431	Build An Array With Stack Operations	Solution	Medium	Array, Simulation
1431	Kids With The Greatest Number Of Candies	Solution	Easy	Array
1423	Maximum Points You Can Obtain From Cards	Solution	Medium	Array, Prefix Sum
1416	Restore The Array	Solution	Hard	Dynamic Programming
1413	Minimum Value To Get Positive Step By Step Sum	Solution	Easy	Array, Prefix Sum
1396	Design Underground System	Solution	Medium	Design
1379	Find A Corresponding Node Of A Binary Tree In A Clone Of That Tree	Solution	Medium	Tree, BFS
1372	Longest Zigzag Path In A Binary Tree	Solution	Medium	Tree, BFS
1359	Count All Valid Pickup And Delivery Options	Solution	Hard	Dynamic Programming, Math
1354	Construct Target Array With Multiple Sums	Solution	Hard	Heap
1345	Jump Game IV	Solution	Hard	Graph, BFS
1342	Number Of Steps To Reduce A Number To Zero	Solution	Easy	Math
1338	Reduce Array Size To The Half	Solution	Medium	Array, Sorting, Heap
1337	The K Weakest Rows In A Matrix	Solution	Easy	Array, Sorting
1332	Remove Palindromic Subsequences	Solution	Easy	String, Two Pointer
1312	Minimum Insertion Steps To Make A String Palindrome	Solution	Hard	Dynamic Programming, String
1305	All Elements In Two Binary Search Trees	Solution	Medium	Tree, DFS, Sorting
1302	Deepest Leaves Sum	Solution	Medium	Tree, DFS
1291	Sequential Digits	Solution	Medium	Enumeration
1288	Remove Covered Intervals	Solution	Medium	Array, Sorting
1286	Iterator For Combination	Solution	Medium	Design, Bit Manipulation
1283	Find The Smallest Divisor Given A Threshold	Solution	Medium	Array, Binary Search
1268	Search Suggestions System	Solution	Medium	Trie
1260	Shift 2D Grid	Solution	Easy	Array, Matrix
1254	Number Of Closed Islands	Solution	Medium	Array, Matrix
1249	Minimum Remove To Make Valid Parentheses	Solution	Medium	Stack
1218	Longest Arithmetic Subsequence Of Given Difference	Solution	Medium	Dynamic Programming
1209	Remove All Adjacent Duplicates in String II	Solution	Medium	String
1202	Smallest String With Swaps	Solution	Medium	Union Find, Graph
1192	Critical Connections In A Network	Solution	Hard	Graph, DFS
1189	Maximum Number Of Balloons	Solution	Easy	String, Counting
1155	Number Of Dice Rolls With Target Sum	Solution	Medium	Dynamic Programming
1143	Longest Common Subsequence	Solution	Medium	Dynamic Programming
1137	N-th Tribonacci Number	Solution	Easy	Dynamic Programming
1108	Defanging an IP Address	Solution	Easy	String
1091	Shortest Path In Binary Matrix	Solution	Medium	Array, Matrix, BFS
1094	Car Pooling	Solution	Medium	Array, Prefix Sum
1049	Last Stone Weight II	Solution	Medium	Dynamic Programming
1048	Longest String Chain	Solution	Medium	Dynamic Programming
1047	Remove All Adjacent Duplicates In String	Solution	Easy	String
1046	Last Stone Weight	Solution	Easy	Heap
1041	Robot Bounded In Circle	Solution	Medium	String
1035	Uncrossed Line	Solution	Medium	Dynamic Programming
1029	Two City Scheduling	Solution	Medium	Array, Greedy
1022	Sum Of Root To Leaf Binary Numbers	Solution	Easy	Tree, DFS
1020	Number Of Enclaves	Solution	Medium	Array, Matrix, DFS, BFS
1014	Best Sight Seeing Pair	Solution	Medium	Dynamic Programming
1010	Pairs Of Songs With Total Durations Divisible By 60	Solution	Medium	Dynamic Programming
1009	Complement Of Base 10 Integer	Solution	Easy	Bit Manipulation
1007	Minimum Domino Rotations For Equal Row	Solution	Medium	Array, Greedy
1004	Max Consecutive Ones III	Solution	Medium	Array, Sliding Window
997	Find The Town Judge	Solution	Easy	Graph
994	Rotting Oranges	Solution	Medium	Array, BFS
993	Cousins In Binary Tree	Solution	Easy	Tree, BFS
991	Broken Calculator	Solution	Medium	Math, Greedy
987	Vertical Order Traversal Of A Binary Tree	Solution	Hard	Tree, DFS
983	Minimum Cost For Tickets	Solution	Medium	Dynamic Programming
981	Time Based Key Value Store	Solution	Medium	Design, Hash Table, Binary Search
980	Unique Paths III	Solution	Hard	Array, Backtracking, Matrix
977	Squares Of A Sorted Array	Solution	Easy	Array, Two Pointers, Sorting
973	K Closest Points To Origin	Solution	Medium	Array, Math, Heap
968	Binary Tree Cameras	Solution	Hard	Tree, DFS
953	Verifying An Alien Dictionary	Solution	Easy	String
946	Validate Stack Sequences	Solution	Easy	Stack
941	Valid Mountain Array	Solution	Easy	Array
931	Minimum Falling Path Sum	Solution	Medium	Dynamic Programming
923	3 Sum With Multiplicity	Solution	Medium	Array, Two Pointers
918	Maximum Sum Circular Subarray	Solution	Medium	Dynamic Programming
917	Reverse Only Letters	Solution	Easy	String, Two Pointers
912	Sort An Array	Solution	Medium	Array, Sorting
905	Sort Array By Parity	Solution	Easy	Array
897	Increasing Order Search Tree	Solution	Easy	Binary Tree, DFS
895	Maximum Frequency Stack	Solution	Hard	Stack
887	Super Egg Drop	Solution	Hard	Dynamic Programming
881	Boats To Save People	Solution	Medium	Array
879	Profitable Schemes	Solution	Hard	Dynamic Programming
877	Stone Game	Solution	Medium	Array
876	Middle Of The Linked List	Solution	Easy	Linked List
875	Koko Eating Bananas	Solution	Medium	Array, Binary Search
871	Minimum Number Of Refueling Stops	Solution	Hard	Dynamic Programming
867	Transpose Matrix	Solution	Easy	Array, Matrix
863	All Nodes Distance K In Binary Tree	Solution	Easy	Tree, Graph, BFS, DFS
856	Score OF Parentheses	Solution	Medium	Stack
852	Peak Index In A Mountain Array	Solution	Medium	Array, Binary Search
849	Maximize Distance To Closest Person	Solution	Medium	Array, Two Pointers
847	Shortest Path Visiting All Nodes	Solution	Hard	Graph, Bit Manipulation
844	Backspace String Compare	Solution	Easy	String, Two Pointers
839	Similar String Groups	Solution	Hard	Graph, DFS, BFS
827	Making A Large Island	Solution	Hard	Array, DFS
820	Shortest Encoding Of Words	Solution	Hard	Array, DFS
799	Champagne Tower	Solution	Medium	Dynamic Programming
785	Is Graph Bipartite?	Solution	Medium	Graph, Bipartite, DFS
784	Letter Case Permutation	Solution	Medium	Backtracking, String
767	Reorganize String	Solution	Medium	Heap
763	Partition Labels	Solution	Medium	String, Two Pointers
746	Min Cost Climbing Stairs	Solution	Easy	Dynamic Programming
745	Prefix And Suffix Search	Solution	Hard	Trie
744	Find Smallest Letter Greater Than Target	Solution	Easy	Array, Binary Search
743	Network Delay Time	Solution	Medium	Graph, DFS, BFS, Shortest Path
740	Delete And Earn	Solution	Medium	Dynamic Programming, Array
739	Daily Temperatures	Solution	Medium	Stack
735	Asteroid Collision	Solution	Medium	Stack
733	Flood Fill	Solution	Easy	Array, DFS
721	Accounts Merge	Solution	Medium	Graph, DFS
714	Best Time to Buy and Sell Stock with Transaction Fee	Solution	Medium	Dynamic Programming
706	Design HashMap	Solution	Easy	Design
705	Design HashSet	Solution	Easy	Design
704	Binary Search	Solution	Easy	Array, Binary Search
703	Kth Largest Element In A Stream	Solution	Easy	Heap, Data Stream
701	Insert Into A Binary Search Tree	Solution	Medium	Tree
700	Search In A Binary Search Tree	Solution	Easy	Tree
698	Partition To K Equal Sum Subsets	Solution	Medium	Backtracking
695	Max Area Of Islands	Solution	Medium	Array, Depth First Search
682	Baseball Game	Solution	Easy	Stack
680	Valid Palindrome II	Solution	Easy	String, Two Pointers
673	Number of Longest Increasing Subsequence	Solution	Medium	Dynamic Programming
669	Trim A Binary Search Tree	Solution	Medium	Tree, Recursion
668	Kth Smallest Number In Multiplication Table	Solution	Hard	Array, Matrix, Binary Search
665	Non-Decreasing Array	Solution	Medium	Array
662	Maximum Width Of Binary Tree	Solution	Medium	Tree, DFS
658	Find K Closest Elements	Solution	Medium	Array, Binary Search
650	2 Keys Keyboard	Solution	Medium	Dynamic Programming
649	Dota2 Senate	Solution	Medium	String, Greedy
647	Palindromic Substrings	Solution	Medium	Dynamic Programming
646	Maximum Length Of Pair Chain	Solution	Medium	Dynamic Programming
637	Average Of Levels In Binary Tree	Solution	Easy	Tree, BFS
630	Course Schedule III	Solution	Hard	Greedy, Heap
617	Merge Two Binary Trees	Solution	Easy	Tree, DFS, BFS
605	Can Place Flowers	Solution	Easy	Array, Greedy
583	Delete Operation For Two Strings	Solution	Medium	Dynamic Programming
581	Shortest Unsorted Continuous Subarray	Solution	Medium	Array, Two Pointers
572	Subtree Of Another Tree	Solution	Easy	Tree
567	Permutation In String	Solution	Medium	String, Two Pointers, Sliding Window
566	Reshape The Matrix	Solution	Easy	Array, Matrix
560	Subarray Sum Equals K	Solution	Medium	Array, Prefix Sum
557	Reverse Words In A String III	Solution	Easy	String
556	Next Greater Element III	Solution	Medium	Math
543	Diameter Of Binary Tree	Solution	Easy	Tree
542	Zero One Matrix	Solution	Medium	Array, Matrix, BFS
540	Single Element In A Sorted Array	Solution	Medium	Array, Binary Search
538	Convert BST To Greater Tree	Solution	Medium	Tree, Recursion
535	Encode And Decode TinyURL	Solution	Medium	Design
532	K Diff Pairs In An Array	Solution	Medium	Array
525	Contiguous Array	Solution	Medium	Array, Prefix Sum
520	Detect Capital	Solution	Easy	String
518	Coin Change II	Solution	Medium	Dynamic Programming
516	Longest Palindromic Subsequence	Solution	Medium	Dynamic Programming
509	Fibonacci Number	Solution	Easy	Dynamic Programming
503	Next Greater Element II	Solution	Medium	Stack
501	Find Mode In Binary Search Tree	Solution	Easy	Tree, BST
496	Next Greater Element I	Solution	Easy	Stack
494	Target Sum	Solution	Medium	Dynamic Programming
485	Max Consecutive Ones	Solution	Easy	Array
474	Ones And Zeroes	Solution	Medium	Dynamic Programming
462	Minimum Moves To Equal Array Elements II	Solution	Medium	Math
461	HammingDistance	Solution	Easy	Bit Manipulation
460	LFU Cache	Solution	Hard	Design
456	132 Pattern	Solution	Medium	Stack
454	4 Sum II	Solution	Medium	Array
452	Minimum Number Of Arrows To Burst Balloons	Solution	Medium	Array, Sorting
450	Delete Node In A BST	Solution	Medium	Tree, BST
448	Find All Numbers Disappeared In An Array	Solution	Easy	Array
443	String Compression	Solution	Medium	String
442	Find All Duplicates In An Array	Solution	Medium	Array
441	Arranging Coins	Solution	Easy	Math
438	Find All Anagrams In A String	Solution	Easy	String, Sliding Window
421	Maximum XOR Of TwoNumbers In An Array	Solution	Medium	Bit Manipulation
417	Pacific Atlantic Water Flow	Solution	Medium	Array, BFS
416	Partition Equal Subset Sum	Solution	Medium	Dynamic Programming
413	Arithmetic Slices	Solution	Medium	Dynamic Programming
412	Fizz Buzz	Solution	Easy	Math
410	Split Array LargestSum	Solution	Hard	Dynamic Programming
409	Longest Palindrome	Solution	Easy	String, Greedy
406	Queue Reconstruction By Height	Solution	Easy	Tree, DFS
404	Sum Of Left Leaves	Solution	Medium	Array, Greedy, Sorting
402	Remove K Digits	Solution	Easy	Tree, DFS
399	Evaluate Division	Solution	Medium	Graph, DFS
398	Random Pick Index	Solution	Medium	Math, Reservoir Sampling, Randomized
394	Decode String	Solution	Medium	Stacks, Depth First Search
392	Is Subsequence	Solution	Easy	String, Two Pointers
389	Find The Difference	Solution	Easy	String
387	First Unique Character In A String	Solution	Easy	String
383	Ransom Note	Solution	Easy	String
382	Linked List Random Node	Solution	Medium	Randomized, Reservoir Sampling, Linked List
381	Insert Delete GetRandom O(1) Duplicates Allowed	Solution	Hard	Design, Randomized
380	Insert Delete GetRandom O(1)	Solution	Medium	Design, Randomized
378	Kth Smallest Element in a Sorted Matrix	Solution	Medium	Array, Matrix
377	Combination Sum IV	Solution	Medium	Array, Dynamic Programming
374	Guess Number Higher Or Lower	Solution	Easy	Binary Search, Interactive
368	Largest Divisible Subset	Solution	Medium	Array
354	Russian Doll Envelopes	Solution	Hard	Dynamic Programming
350	Intersection Of Two Arrays II	Solution	Easy	Array
349	Intersection Of Two Arrays	Solution	Easy	Array
347	Top K Frequent Elements	Solution	Medium	Heap
344	Reverse String	Solution	Easy	String
341	Flatten Nested List Iterator	Solution	Medium	Design, Iterator
338	Counting Bits	Solution	Easy	Dynamic Programming, Bit Manipulation
337	House Robber III	Solution	Medium	Dynamic Programming, Tree
329	Longest Increasing Path In A Matrix	Solution	Hard	Dynamic Programming, DFS
328	Odd Even Linked List	Solution	Medium	Linked List
327	Count Of Range Sum	Solution	Hard	Array, Merge Sort
323	Number Of Connected Components In An Undirected Graph	Solution	Medium	Graph, BFS
322	Coin Change	Solution	Medium	Dynamic Programming
320	Generalized Abbreviation	Solution	Medium	Backtracking
319	Bulb Switcher	Solution	Medium	Math
318	Maximum Product Of Word Lengths	Solution	Medium	String
316	Remove Duplicate Characters	Solution	Medium	String, Greedy
312	Burst Balloons	Solution	Hard	Dynamic Programming
310	Minimum Height Trees	Solution	Medium	Graph, Tree, BFS
309	Best Time to Buy and Sell Stock with Cooldown	Solution	Medium	Dynamic Programming
304	Range Sum Query 2D - Immutable	Solution	Medium	Dynamic Programming
303	Range Sum Query - Immutable	Solution	Easy	Dynamic Programming
300	Longest Increasing Subsequence	Solution	Medium	Dynamic Programming
297	Serialize And Deserialize Binary Tree	Solution	Hard	Design, Binary Tree
295	Find Median From Data Stream	Solution	Hard	Heap
290	Word Pattern	Solution	Easy	String
289	Game Of Life	Solution	Medium	Array, Matrix
287	Find The Duplicate Number	Solution	Medium	Array, Two Pointers
284	Peeking Iterator	Solution	Medium	Design, Iterator
283	Move Zeroes	Solution	Easy	Array
279	Perfect Squares	Solution	Medium	Dynamic Programming
278	First Bad Version	Solution	Easy	Array, Binary Search
268	Missing Number	Solution	Easy	Array, Math
264	Ugly Number II	Solution	Medium	Dynamic Programming
261	Graph Valid Tree	Solution	Medium	Graph, Tree, BFS
258	Add Digits	Solution	Easy	Math
257	Binary Tree Paths	Solution	Easy	Backtracking
252	Meeting Rooms	Solution	Easy	Array, Sorting
242	Valid Anagram	Solution	Easy	String
240	Search A 2D Matrix II	Solution	Medium	Array, Matrix
238	Product Of Array Except Self	Solution	Medium	Array, Prefix Sum
236	Lowest Common Ancestor Of A Binary Tree	Solution	Medium	Binary Tree, DFS
235	Lowest Common Ancestor Of A Binary Search Tree	Solution	Medium	Binary Tree, Binary Search Tree, BFS, DFS
234	Palindrome Linked List	Solution	Easy	Linked List, Two Pointers
232	Implement Queue Using Stacks	Solution	Easy	Design, Stack, Queue
231	Power Of Two	Solution	Easy	Bit Manipulation, Math
230	Kth Smallest Element In A BST	Solution	Medium	Tree, DFS
228	Summary Ranges	Solution	Easy	Array
226	Invert Binary Tree	Solution	Easy	Tree
225	Implement Stack Using Queues	Solution	Easy	Stack, Queue
222	Count Complete Tree Node	Solution	Medium	Tree, DFS
221	Maximal Square	Solution	Medium	Dynamic Programming
217	Contains Duplicate	Solution	Easy	Array
216	Combination Sum III	Solution	Medium	Backtracking
215	Kth Largest Element In An Array	Solution	Medium	Array, Quick Select
213	House Robber II	Solution	Medium	Dynamic Programming
212	Word Search II	Solution	Hard	Array, Matrix, Backtracking, DFS, Trie
211	Design Add And Search Words Data Structure	Solution	Medium	Design, Trie, DFS
210	Course Schedule II	Solution	Medium	Graph, DFS
208	Implement Trie (Prefix Tree)	Solution	Medium	Design, Trie
207	Course Schedule	Solution	Medium	Graph, DFS
206	Reverse Linked List	Solution	Easy	Linked List
203	Remove Linked List Elements	Solution	Easy	Linked List
202	Happy Number	Solution	Easy	Math
201	Bitwise AND Of Numbers Range	Solution	Medium	Bit Manipulation
200	Number Of Islands	Solution	Medium	Array, Matrix, DFS
199	Binary Tree Right Side View	Solution	Medium	Tree, BFS
198	House Robber	Solution	Easy	Dynamic Programming
191	Number Of 1 Bits	Solution	Easy	Bit Manipulation
190	Reverse Bits	Solution	Easy	Bit Manipulation
189	Rotate Array	Solution	Easy	Array, Two Pointers
188	Best Time To Buy And Sell Stock IV	Solution	Hard	Dynamic Programming
174	Dungeon Game	Solution	Hard	Dynamic Programming
173	Binary Search Tree Iterator	Solution	Medium	Tree
171	Excel Sheet Column Number	Solution	Easy	Math, String
169	Majority Element	Solution	Easy	Array
167	Two Sum II - Input Array Is Sorted	Solution	Easy	Array
165	Compare Version Numbers	Solution	Medium	String, Two Pointers
162	Find Peak Element	Solution	Medium	Array, Binary Search
160	Intersection Of Two Linked Lists	Solution	Easy	Linked List, Two Pointers
155	Min Stack	Solution	Medium	Stack
153	Find Minimum In rotated Sorted Array	Solution	Medium	Array, Binary Search
152	Maximum Product Subarray	Solution	Medium	Dynamic Programming, Array
151	Reverse Words In A String	Solution	Medium	String
150	Evaluate Reverse Polish Notation	Solution	Medium	Stack, String
148	Sort List	Solution	Medium	Linked List, Sorting
146	LRU Cache	Solution	Medium	Design
145	Binary Tree Postorder Traversal	Solution	Easy	Tree
144	Binary Tree Preorder Traversal	Solution	Easy	Tree
142	Linked List Cycle II	Solution	Medium	Linked List, Two Pointers
141	Linked List Cycle	Solution	Easy	Linked List, Two Pointers
139	Word Break	Solution	Medium	Dynamic Programming
138	Copy List With Random Pointer	Solution	Medium	Linked List
136	Single Number	Solution	Easy	Bit Manipulation, Array
135	Candy	Solution	Hard	Array, Greedy
134	Gas Station	Solution	Medium	Array, Greedy
133	Clone Graph	Solution	Medium	Graph
131	Palindrome Partitioning	Solution	Medium	Backtracking, String
130	Surrounded Regions	Solution	Medium	Array, Matrix, DFS
129	Sum Root To Leaf Numbers	Solution	Medium	Tree, DFS
128	Longest Consecutive Sequence	Solution	Medium	Array
127	Word Ladder	Solution	Hard	String, BFS
125	Valid Palindrome	Solution	Easy	String, Two Pointers
123	Best Time To Buy And Sell Stock III	Solution	Hard	Dynamic Programming
122	Best Time To Buy And Sell Stock II	Solution	Easy	Dynamic Programming
121	Best Time To Buy And Sell Stock	Solution	Easy	Dynamic Programming
120	Triangle	Solution	Medium	Dynamic Programming
118	Pascal's Triangle	Solution	Easy	Dynamic Programming
117	Populating Next Right Pointers In Each Node II	Solution	Medium	Tree, DFS
116	Populating Next Right Pointers In Each Node	Solution	Medium	Tree, BFS
112	Path Sum	Solution	Easy	Tree, DFS
111	Minimum Depth Of Binary Tree	Solution	Easy	Tree, BFS
110	Balanced Binary Tree	Solution	Easy	Tree, DFS
108	Convert Sorted Array To Binary Search Tree	Solution	Easy	Tree
107	Binary Tree Level Order Traversal II	Solution	Medium	Tree, BFS
104	Maximum Depth Of Binary Tree	Solution	Easy	Tree
103	Binary Tree Zigzag Level Order Traversal	Solution	Medium	Tree, BFS
102	Binary Tree Level Order Traversal	Solution	Medium	Tree, BFS
101	Symmetric Tree	Solution	Easy	Tree
100	Same Tree	Solution	Easy	Tree, DFS, BFS
99	Recover Binary Search Tree	Solution	Medium	Tree, Morris Traversal
98	Validate Binary Search Tree	Solution	Medium	Tree
96	Unique Binary Search Trees	Solution	Medium	Dynamic Programming, Tree
95	Unique Binary Search Trees II	Solution	Medium	Tree
94	Binary Tree Inorder Traversal	Solution	Easy	Tree, Stack, DFS
91	Decode Ways	Solution	Medium	Dynamic Programming, String
90	Subsets II	Solution	Medium	Backtracking, String
88	Merge Sorted Array	Solution	Easy	Array, Two Pointer, Sorting
84	Largest Rectangle In Histogram	Solution	Hard	Stack, Array
83	Remove Duplicates From Sorted List	Solution	Easy	Linked List
82	Remove Duplicates From Sorted List II	Solution	Medium	Linked List
81	Search In Rotated Sorted Array II	Solution	Medium	Array, Binary Search
80	Remove Duplicates In Sorted Array II	Solution	Medium	Array
79	Word Search	Solution	Medium	Array, Matrix, Backtracking, DFS
78	Subsets	Solution	Medium	Bit Manipulation
77	Combinations	Solution	Medium	Backtracking
75	Sort Colors	Solution	Medium	Array, Two Pointers
74	Search A 2D Matrix	Solution	Medium	Array, Matrix
73	Set Matrix Zeroes	Solution	Medium	Array, Matrix, Simulation
72	Edit Distance	Solution	Hard	Dynamic Programming
71	Simplify Path	Solution	Medium	Stack
70	Climbing Stairs	Solution	Easy	Dynamic Programming
68	Text Justification	Solution	Hard	String, Simulation
67	Add Binary	Solution	Easy	Math, String, Bit Manipulation
64	Minimum Path Sum	Solution	Medium	Dynamic Programming
63	Unique Paths II	Solution	Medium	Dynamic Programming
62	Unique Paths	Solution	Medium	Dynamic Programming
61	Rotate List	Solution	Medium	Linked List, Two Pointers
59	Spiral Matrix II	Solution	Medium	Array, Matrix
57	Insert Interval	Solution	Medium	Array
56	Merge Intervals	Solution	Medium	Array
55	Jump Game	Solution	Medium	Dynamic Programming
54	Spiral Matrix	Solution	Medium	Array, Matrix
53	Maximum Subarray	Solution	Easy	Array
52	N-Queens II	Solution	Hard	Backtracking
51	N-Queens	Solution	Hard	Backtracking, Array
49	Group Anagrams	Solution	Medium	String
48	Rotate Image	Solution	Medium	Array, Matrix
47	Permutations II	Solution	Medium	Backtracking
46	Permutations	Solution	Medium	Backtracking
45	Jump Game II	Solution	Medium	Dynamic Programming
42	Trapping Rain Water	Solution	Hard	Dynamic Programming
41	First Missing Positive	Solution	Hard	Array
40	Combination Sum II	Solution	Medium	Array, Backtracking
39	Combination Sum	Solution	Medium	Array, Backtracking
37	Sudoku Solver	Solution	Medium	Array, Matrix, Backtracking
36	Valid Sudoku	Solution	Medium	Array, Matrix
35	Search Insert Position	Solution	Easy	Array, Binary Search
33	Search In Rotated Sorted Array	Solution	Medium	Array, Binary Search
32	Longest Valid Parentheses	Solution	Hard	String, Two Pointers
31	Next Permutation	Solution	Medium	Array, Two Pointers
29	Divide Two Integers	Solution	Medium	Bit Manipulation, Math
27	Remove Element	Solution	Easy	Array
26	Remove Duplicates In Sorted Array	Solution	Easy	Array
24	Swap Nodes in Pairs	Solution	Easy	Linked List
23	Merge K Sorted Lists	Solution	Hard	Linked List
22	Generate Parentheses	Solution	Medium	Backtracking
21	Merge Two Sorted Lists	Solution	Easy	Linked List
20	Valid Parentheses	Solution	Easy	Stack
19	Remove Nth Node From End Of List	Solution	Medium	Linked List
17	Letter Combinations Of A Phone Number	Solution	Medium	String, Recursion
15	3 Sum	Solution	Medium	Array
14	Longest Common Prefix	Solution	Easy	String
13	Roman To Integer	Solution	Easy	Math
12	Integer Roman	Solution	Medium	Math
11	Container With Most Water	Solution	Medium	Array, Greedy
9	Palindrome Number	Solution	Easy	Math
8	String To Integer (atoi)	Solution	Medium	String
7	Reverse Integer	Solution	Medium	Math
6	Zigzag Conversion	Solution	Medium	String, Simulation
5	Longest Palindromic Substring	Solution	Medium	String, Two Pointers
4	Median Of Two Sorted Arrays	Solution	Hard	Array, Binary Search
3	Longest Substring Without Repeating Characters	Solution	Medium	String, Sliding Window
2	Add Two Numbers	Solution	Medium	Linked List
1	Two Sum	Solution	Easy	Array

Work At Tech

Arrays

#	Title	Solutions	Difficulty	Tag
1	Cumulative Sum	Solution	Easy	Arrays
2	Positive Cumulative Sum	Solution	Easy	Arrays
3	Identical Twins	Solution	Easy	Arrays

Binary Trees

#	Title	Solutions	Difficulty	Tag
1	Binary Tree Inorder Traversal	Solution	Easy	Binary Trees

Dynamic Programming

#	Title	Solutions	Difficulty	Tag
1	Climbing Stairs	Solution	Easy	Dynamic Programming
2	Longest Increasing Subsequence (LIS)	Solution	Medium	Dynamic Programming
3	Longest Common Subsequence (LCS)	Solution	Medium	Dynamic Programming
4	Maximum Sum Increasing Subsequence	Solution	Medium	Dynamic Programming
5	Longest Palindromic Substring (LPS)	Solution	Medium	Dynamic Programming
6	Edit Distance (Levenshtein Distance)	Solution	Medium	Dynamic Programming
7	Collect Jewels	Solution	Medium	Dynamic Programming
8	Subset Sum	Solution	Medium	Dynamic Programming
9	Subset Sum 2	Solution	Medium	Dynamic Programming
10	Maximum Path Sum In Matrix	Solution	Medium	Dynamic Programming
11	Rod Cutting	Solution	Medium	Dynamic Programming
12	Coin Change	Solution	Medium	Dynamic Programming
13	Decode Ways	Solution	Medium	Dynamic Programming
14	Unique Paths	Solution	Medium	Dynamic Programming
15	Maximum Product Subarray	Solution	Medium	Dynamic Programming

Graph

#	Title	Solutions	Difficulty	Tag
1	Adjacency List To Adjacency Matrix	Solution	Easy	Graph
2	Adjacency Matrix To Adjacency List	Solution	Easy	Graph
3	Edges To Adjacency Matrix	Solution	Easy	Graph
4	Edges To Adjacency List	Solution	Easy	Graph
5	DFS Of An Acyclic Graph	Solution	Medium	Graph
6	DFS Of A Cyclic Graph	Solution	Medium	Graph
7	BFS Of A Graph	Solution	Medium	Graph
8	Clone A Graph	Solution	Medium	Graph
9	Detect Cycle In Directed Graph	Solution	Medium	Graph
10	Detect Cycle In Undirected Graph	Solution	Medium	Graph
11	Valid Course Schedule	Solution	Medium	Graph
12	Paths Exists In Directed Graph	Solution	Medium	Graph
13	Flood Fill Image	Solution	Easy	Graph
14	Number Of Islands	Solution	Medium	Graph
15	Valid Path	Solution	Medium	Graph
16	Capture Surrounded Regions	Solution	Medium	Graph
18	Knight's Journey On A Chess Board	Solution	Medium	Graph
19	Word Search Board	Solution	Medium	Graph
21	Word Ladder	Solution	Hard	Graph

Greedy Algorithm

#	Title	Solutions	Difficulty	Tag
1	Max Meetings In A Room	Solution	Medium	Greedy
2	Sack Of Grains	Solution	Medium	Greedy
3	Tasks For Profit	Solution	Medium	Greedy
4	Trains And Platforms	Solution	Medium	Greedy