LeetCode

Algorithms

#	Title	Solution	Difficulty
1	Two Sum	Ruby	Easy
2	Add Two Numbers	Ruby	Medium
3	Longest Substring Without Repeating Characters	Ruby	Medium
4	Median of Two Sorted Arrays	Ruby	Hard
5	Longest Palindromic Substring	Ruby	Medium
6	Verifying an Alien Dictionary	Ruby	Medium
7	Reverse Integer	Ruby	Medium
8	String to Integer (atoi)	Ruby	Medium
9	Palindrome Number	Ruby	Easy
10	Regular Expression Matching	Ruby	Hard
11	Container With Most Water	Ruby	Medium
12	Integer to Roman	Ruby	Medium
13	Roman to Integer	Ruby	Easy
14	Longest Common Prefix	Ruby	Easy
15	3Sum	Ruby	Medium
16	3Sum Closest	Ruby	Medium
17	Letter Combinations of a Phone Number	Ruby	Medium
18	4Sum	Ruby	Medium
19	Remove Nth Node From End of List	Ruby	Medium
20	Valid Parentheses	Ruby	Easy
21	Merge Two Sorted Lists	Ruby	Easy
22	Generate Parentheses	Ruby	Medium
23	Merge k Sorted Lists	Ruby	Hard
24	Swap Nodes in Pairs	Ruby	Medium
25	Reverse Nodes in k-Group	Ruby	Hard
26	Remove Duplicates from Sorted Array	Ruby	Easy
27	Remove Element	Ruby	Easy
28	Find the Index of the First Occurrence in a String	Ruby	Medium
30	Substring with Concatenation of All Words	Ruby	Hard
33	Search in Rotated Sorted Array	Ruby	Medium
34	Find First and Last Position of Element in Sorted Array	Ruby	Medium
35	Search Insert Position	Ruby	Easy
36	Valid Sudoku	Ruby	Medium
39	Combination Sum	Ruby	Medium
40	Combination Sum II	Ruby	Medium
42	Trapping Rain Water	Ruby	Hard
43	Multiply Strings	Ruby	Medium
45	Jump Game II	Ruby	Medium
46	Permutations	Ruby	Medium
48	Rotate Image	Ruby	Medium
49	Group Anagrams	Ruby	Medium
50	Pow(x, n)	Ruby	Medium
52	N-Queens II	Ruby	Hard
53	Maximum Subarray	Ruby	Medium
54	Spiral Matrix	Ruby	Medium
55	Jump Game	Ruby	Medium
58	Length of Last Word	Ruby	Easy
59	Spiral Matrix II	Ruby	Medium
61	Rotate List	Ruby	Medium
62	Unique Paths	Ruby	Medium
63	Unique Paths II	Ruby	Medium
64	Minimum Path Sum	Ruby	Medium
66	Plus One	Ruby	Easy
67	Add Binary	Ruby Python3	Easy
68	Text Justification	Ruby	Hard
69	Sqrt(x)	Ruby	Easy
70	Climbing Stairs	Ruby	Easy
71	Climbing Stairs	Ruby	Medium
72	Edit Distance	Ruby	Hard
73	Set Matrix Zeroes	Ruby	Medium
74	Search a 2D Matrix	Ruby	Medium
76	Minimum Window Substring	Ruby	Hard
77	Combinations	Ruby	Medium
79	Word Search	Ruby	Medium
80	Remove Duplicates from Sorted Array II	Ruby	Medium
81	Search in Rotated Sorted Array II	Ruby	Medium
82	Remove Duplicates from Sorted List II	Ruby	Medium
86	Partition List	Ruby	Medium
87	Scramble String	Ruby	Hard
88	Merge Sorted Array	Ruby	Easy
91	Decode Ways	Ruby	Medium
92	Reverse Linked List II	Ruby	Medium
94	Binary Tree Inorder Traversal	Ruby	Easy
95	Unique Binary Search Trees II	Ruby	Medium
97	Interleaving String	Ruby	Medium
98	Validate Binary Search Tree	Ruby	Medium
100	Same Tree	Ruby	Easy
101	Symmetric Tree	Ruby	Easy
102	Binary Tree Level Order Traversal	Ruby	Medium
103	Binary Tree Zigzag Level Order Traversal	Ruby	Medium
104	Maximum Depth of Binary Tree	Ruby Python3	Easy
105	Construct Binary Tree from Preorder and Inorder Traversal	Ruby	Medium
106	Construct Binary Tree from Inorder and Postorder Traversal	Ruby	Medium
108	Convert Sorted Array to Binary Search Tree	Ruby	Easy
109	Convert Sorted List to Binary Search Tree	Ruby	Medium
110	Balanced Binary Tree	Ruby	Easy
111	Minimum Depth of Binary Tree	Ruby	Easy
112	Path Sum	Ruby	Easy
113	Path Sum II	Ruby	Medium
114	Flatten Binary Tree to Linked List	Ruby	Medium
117	Populating Next Right Pointers in Each Node II	Ruby	Medium
118	Pascal's Triangle	Ruby	Easy
119	Pascal's Triangle II	Ruby	Easy
120	Triangle	Ruby	Medium
121	Best Time to Buy and Sell Stock	Ruby	Easy
122	Best Time to Buy and Sell Stock II	Ruby	Medium
123	Best Time to Buy and Sell Stock III	Ruby	Hard
124	Binary Tree Maximum Path Sum	Ruby	Hard
125	Valid Palindrome	Ruby	Easy
127	Word Ladder	Ruby	Hard
128	Longest Consecutive Sequence	Ruby	Medium
129	Sum Root to Leaf Numbers	Ruby	Medium
130	Surrounded Regions	Ruby	Medium
133	Clone Graph	Ruby	Medium
134	Gas Station	Ruby	Easy
135	Candy	Ruby	Hard
136	Single Number	Ruby	Easy
137	Single Number II	Ruby	Medium
138	Copy List with Random Pointer	Ruby	Medium
139	Word Break	Ruby	Medium
141	Linked List Cycle	Ruby	Easy
142	Linked List Cycle II	Ruby	Medium
146	LRU Cache	Ruby	Medium
148	Sort List	Ruby	Medium
149	Max Points on a Line	Ruby	Hard
150	Evaluate Reverse Polish Notation	Ruby	Medium
151	Reverse Words in a String	Ruby	Medium
152	Maximum Product Subarray	Ruby	Medium
153	Find Minimum in Rotated Sorted Array	Ruby	Medium
155	Min Stack	Ruby	Medium
162	Find Peak Element	Ruby	Medium
167	Two Sum II - Input Array Is Sorted	Ruby	Medium
168	Excel Sheet Column Title	Ruby	Easy
169	Majority Element	Ruby	Easy
172	Factorial Trailing Zeroes	Ruby	Medium
173	Binary Search Tree Iterator	Ruby	Medium
188	Best Time to Buy and Sell Stock IV	Ruby	Hard
189	Rotate Array	Ruby	Medium
190	Reverse Bits	Ruby	Easy
191	Number of 1 Bits	Ruby	Easy
198	House Robber	Ruby	Medium
199	Binary Tree Right Side View	Ruby	Medium
200	Number of Islands	Ruby	Medium
201	Bitwise AND of Numbers Range	Ruby	Medium
202	Happy Number	Ruby	Easy
205	Isomorphic Strings	Ruby	Easy
206	Reverse Linked List	Ruby	Easy
207	Course Schedule	Ruby	Medium
208	Implement Trie (Prefix Tree)	Ruby	Medium
209	Minimum Size Subarray Sum	Ruby	Medium
210	Course Schedule II	Ruby	Medium
211	Design Add and Search Words Data Structure	Ruby	Medium
212	Word Search II	Ruby	Hard
215	Kth Largest Element in an Array	Ruby	Medium
216	Combination Sum III	Ruby	Medium
219	Contains Duplicate II	Ruby	Easy
221	Maximal Square	Ruby	Medium
222	Count Complete Tree Nodes	Ruby	Medium
224	Basic Calculator	Ruby	Hard
225	Implement Stack using Queues	Ruby	Easy
226	Invert Binary Tree	Ruby	Easy
227	Basic Calculator II	Ruby	Medium
228	Summary Ranges	Ruby	Easy
229	Majority Element II	Ruby	Medium
230	Kth Smallest Element in a BST	Ruby	Medium
232	Implement Queue using Stacks	Ruby	Easy
234	Palindrome Linked List	Ruby	Easy
235	Lowest Common Ancestor of a Binary Search Tree	Ruby	Medium
236	Lowest Common Ancestor of a Binary Tree	Ruby	Medium
238	Product of Array Except Self	Ruby	Medium
239	Sliding Window Maximum	Ruby	Hard
242	Valid Anagram	Ruby	Easy
258	Add Digits	Ruby	Easy
274	H-Index	Ruby	Medium
278	First Bad Version	Ruby	Easy
283	Move Zeroes	Ruby	Easy
287	Find the Duplicate Number	Ruby	Medium
289	Game of Life	Ruby	Medium
290	Word Pattern	Ruby	Easy
295	Find Median from Data Stream	Ruby	Hard
299	Bulls and Cows	Ruby Python3	Medium
300	Longest Increasing Subsequence	Ruby	Medium
316	Remove Duplicate Letters	Ruby	Medium
319	Bulb Switcher	Ruby	Medium
322	Coin Change	Ruby	Medium
328	Odd Even Linked List	Ruby	Medium
332	Reconstruct Itinerary	Ruby	Hard
334	Increasing Triplet Subsequence	Ruby	Medium
338	Counting Bits	Ruby	Easy
341	Flatten Nested List Iterator	Ruby	Medium
342	Power of Four	Ruby	Easy
343	Integer Break	Ruby	Medium
344	Reverse String	Ruby	Easy
345	Reverse Vowels of a String	Ruby	Easy
347	Top K Frequent Elements	Ruby	Medium
373	Find K Pairs with Smallest Sums	Ruby	Medium
374	Guess Number Higher or Lower	Ruby	Easy
377	Combination Sum IV	Ruby	Medium
380	Insert Delete GetRandom O(1)	Ruby	Medium
382	Linked List Random Node	Ruby	Medium
383	Ransom Note	Ruby	Easy
387	First Unique Character in a String	Ruby	Easy
389	Find the Difference	Ruby	Easy
392	Is Subsequence	Ruby	Easy
394	Decode String	Ruby	Medium
399	Evaluate Division	Ruby	Medium
403	Frog Jump	Ruby	Hard
409	Longest Palindrome	Ruby	Easy
416	Partition Equal Subset Sum	Ruby	Medium
417	Pacific Atlantic Water Flow	Ruby	Medium
424	Longest Repeating Character Replacement	Ruby	Medium
427	Construct Quad Tree	Ruby	Medium
432	All O`one Data Structure	Ruby	Hard
433	Minimum Genetic Mutation	Ruby	Medium
435	Non-overlapping Intervals	Ruby	Medium
437	Path Sum III	Ruby	Medium
438	Find All Anagrams in a String	Ruby	Medium
443	String Compression	Ruby Python3	Medium
445	Add Two Numbers II	Ruby	Medium
450	Delete Node in a BST	Ruby	Medium
452	Minimum Number of Arrows to Burst Balloons	Ruby	Medium
455	Assign Cookies	Ruby	Easy
456	132 Pattern	Ruby	Medium
458	Poor Pigs	Ruby	Hard
459	Repeated Substring Pattern	Ruby	Easy
486	Predict the Winner	Ruby	Medium
501	Find Mode in Binary Search Tree	Ruby	Easy
502	IPO	Ruby Python3	Hard
509	Fibonacci Number	Ruby	Easy
515	Find Largest Value in Each Tree Row	Ruby	Medium
516	Longest Palindromic Subsequence	Ruby	Medium
518	Coin Change II	Ruby	Medium
530	Minimum Absolute Difference in BST	Ruby	Easy
539	Minimum Time Difference	Ruby	Medium
540	Single Element in a Sorted Array	Ruby	Medium
542	01 Matrix	Ruby	Medium
543	Diameter of Binary Tree	Ruby	Easy
547	Number of Provinces	Ruby	Medium
557	Reverse Words in a String III	Ruby	Easy
567	Permutation in String	Ruby	Medium
589	N-ary Tree Preorder Traversal	Ruby	Easy
605	Can Place Flowers	Ruby	Easy
606	Construct String from Binary Tree	Ruby	Easy
621	Task Scheduler	Ruby	Medium
622	Design Circular Queue	Ruby	Medium
624	Maximum Distance in Arrays	Ruby	Medium
637	Average of Levels in Binary Tree	Ruby	Easy
643	Maximum Average Subarray I	Ruby	Easy
646	Maximum Length of Pair Chain	Ruby	Medium
649	Dota2 Senate	Ruby	Medium
652	Find Duplicate Subtrees	Ruby	Medium
661	Image Smoother	Ruby	Easy
662	Maximum Width of Binary Tree	Ruby	Medium
664	Strange Printer	Ruby	Hard
670	Maximum Swap	Ruby	Medium
673	Number of Longest Increasing Subsequence	Ruby	Medium
688	Knight Probability in Chessboard	Ruby	Medium
692	Top K Frequent Words	Ruby	Medium
700	Search in a Binary Search Tree	Ruby	Easy
703	Kth Largest Element in a Stream	Ruby	Easy
704	Binary Search	Ruby	Easy
705	Design HashSet	Ruby	Easy
706	Design HashMap	Ruby	Easy
712	Minimum ASCII Delete Sum for Two Strings	Ruby	Medium
714	Best Time to Buy and Sell Stock with Transaction	Ruby	Medium
724	Find Pivot Index	Ruby	Easy
725	Split Linked List in Parts	Ruby	Medium
733	Flood Fill	Ruby	Easy
735	Asteroid Collision	Ruby	Medium
739	Daily Temperatures	Ruby	Medium
744	Find Smallest Letter Greater Than Target	Ruby	Easy
746	Min Cost Climbing Stairs	Ruby	Easy
767	Reorganize String	Ruby	Medium
773	Sliding Puzzle	Ruby	Hard
779	K-th Symbol in Grammar	Ruby	Medium
783	Minimum Distance Between BST Nodes	Ruby Python3	Easy
785	Is Graph Bipartite?	Ruby	Medium
790	Domino and Tromino Tiling	Ruby	Medium
796	Rotate String	Ruby	Easy
799	Champagne Tower	Ruby	Medium
802	Find Eventual Safe States	Ruby	Medium
808	Soup Servings	Ruby	Medium
815	Bus Routes	Ruby	Hard
823	Binary Trees With Factors	Ruby	Medium
837	New 21 Game	Ruby	Medium
839	Similar String Groups	Ruby	Hard
841	Backspace String Compare	Ruby	Medium
844	Backspace String Compare	Ruby	Easy
847	Shortest Path Visiting All Nodes	Ruby	Hard
852	Peak Index in a Mountain Array	Ruby	Medium
859	Buddy Strings	Ruby	Easy
862	Shortest Subarray with Sum at Least K	Ruby	Hard
863	All Nodes Distance K in Binary Tree	Ruby	Medium
864	Backspace String Compare	Ruby	Hard
867	Transpose Matrix	Ruby	Easy
872	Leaf-Similar Trees	Ruby	Medium
875	Koko Eating Bananas	Ruby Python3	Medium
876	Middle of the Linked List	Ruby	Easy
879	Profitable Schemes	Ruby	Hard
880	Decoded String at Index	Ruby	Medium
881	Middle of the Linked List	Ruby	Medium
884	Uncommon Words from Two Sentences	Ruby	Easy
894	All Possible Full Binary Trees	Ruby	Medium
896	Monotonic Array	Ruby	Easy
901	Online Stock Span	Ruby	Medium
904	Fruit Into Baskets	Ruby	Medium
905	Sort Array By Parity	Ruby	Easy
909	Snakes and Ladders	Ruby	Medium
912	Sort an Array	Ruby	Medium
918	Maximum Sum Circular Subarray	Ruby	Medium
920	Number of Music Playlists	Ruby	Hard
933	Number of Recent Calls	Ruby	Easy
934	Shortest Bridge	Ruby	Medium
935	Knight Dialer	Ruby	Medium
946	Validate Stack Sequences	Ruby	Medium
947	Most Stones Removed with Same Row or Column	Ruby	Medium
953	Verifying an Alien Dictionary	Ruby	Easy
956	Tallest Billboard	Ruby	Hard
958	Check Completeness of a Binary Tree	Ruby	Medium
983	Minimum Cost For Tickets	Ruby	Medium
989	Add to Array-Form of Integer	Ruby	Easy
990	Satisfiability of Equality Equations	Ruby	Medium
994	Rotting Oranges	Ruby	Medium
1004	Max Consecutive Ones III	Ruby	Medium
1011	Capacity To Ship Packages Within D Days	Ruby	Medium
1020	Number of Enclaves	Ruby	Medium
1027	Longest Arithmetic Subsequence	Ruby	Medium
1035	Uncrossed Lines	Ruby	Medium
1046	Last Stone Weight	Ruby	Easy
1048	Longest String Chain	Ruby	Medium
1071	Greatest Common Divisor of Strings	Ruby	Easy
1072	Flip Columns For Maximum Number of Equal Rows	Ruby	Medium
1091	Shortest Path in Binary Matrix	Ruby	Medium
1106	Parsing A Boolean Expression	Ruby	Hard
1125	Smallest Sufficient Team	Ruby	Hard
1129	Shortest Path with Alternating Colors	Ruby	Medium
1137	N-th Tribonacci Number	Ruby	Easy
1140	Stone Game II	Ruby	Medium
1143	Longest Common Subsequence	Ruby	Medium
1146	Snapshot Array	Ruby	Medium
1155	Number of Dice Rolls With Target Sum	Ruby	Medium
1160	Find Words That Can Be Formed by Characters	Ruby	Easy
1161	Maximum Level Sum of a Binary Tree	Ruby	Medium
1162	As Far from Land as Possible	Ruby	Medium
1187	Make Array Strictly Increasing	Ruby	Hard
1203	Sort Items by Groups Respecting Dependencies	Ruby	Hard
1207	Unique Number of Occurrences	Ruby	Easy
1218	Longest Arithmetic Subsequence of Given Difference	Ruby	Medium
1220	Count Vowels Permutation	Ruby	Hard
1232	Check If It Is a Straight Line	Ruby	Easy
1233	Remove Sub-Folders from the Filesystem	Ruby	Medium
1239	Maximum Length of a Concatenated String with Unique Characters	Ruby	Medium
1254	Number of Closed Islands	Ruby	Medium
1266	Minimum Time Visiting All Points	Ruby	Easy
1268	Search Suggestions System	Ruby	Medium
1269	Number of Ways to Stay in the Same Place After Some Steps	Ruby	Hard
1277	Count Square Submatrices with All Ones	Ruby	Medium
1282	Group the People Given the Group Size They Belong To	Ruby	Medium
1287	Element Appearing More Than 25% In Sorted Array	Ruby	Easy
1318	Minimum Flips to Make a OR b Equal to c	Ruby	Medium
1319	Number of Operations to Make Network Connected	Ruby	Medium
1326	Minimum Number of Taps to Open to Water a Garden	Ruby	Hard
1337	The K Weakest Rows in a Matrix	Ruby	Easy
1351	Count Negative Numbers in a Sorted Matrix	Ruby	Easy
1359	Count All Valid Pickup and Delivery Options	Ruby	Hard
1372	Longest ZigZag Path in a Binary Tree	Ruby	Medium
1345	Jump Game IV	Ruby	Hard
1361	Validate Binary Tree Nodes	Ruby	Medium
1371	Find the Longest Substring Containing Vowels in Even Counts	Ruby	Medium
1376	Time Needed to Inform All Employees	Ruby	Medium
1381	Design a Stack With Increment Operation	Ruby	Medium
1396	Design Underground System	Ruby	Medium
1402	Reducing Dishes	Ruby	Hard
1405	Longest Happy String	Ruby	Medium
1406	Stone Game III	Ruby	Hard
1416	Restore The Array	Ruby	Hard
1420	Build Array Where You Can Find The Maximum Exactly K Comparisons	Ruby	Hard
1422	Maximum Score After Splitting a String	Ruby	Easy
1424	Diagonal Traverse II	Ruby	Medium
1425	Constrained Subsequence Sum	Ruby	Hard
1431	Kids With the Greatest Number of Candies	Ruby	Easy
1436	1436. Destination City	Ruby	Easy
1441	Build an Array With Stack Operations	Ruby	Medium
1444	Number of Ways of Cutting a Pizza	Ruby Python3	Hard
1448	Count Good Nodes in Binary Tree	Ruby	Medium
1456	Maximum Number of Vowels in a Substring of Given Length	Ruby	Medium
1457	Pseudo-Palindromic Paths in a Binary Tree	Ruby	Medium
1458	Max Dot Product of Two Subsequences	Ruby	Hard
1464	Maximum Product of Two Elements in an Array	Ruby	Easy
1466	Reorder Routes to Make All Paths Lead to the City Zero	Ruby	Medium
1470	Shuffle the Array	Ruby	Easy
1472	Design Browser History	Ruby	Medium
1480	Running Sum of 1d Array	Ruby	Easy
1489	Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree	Ruby	Hard
1491	Average Salary Excluding the Minimum and Maximum Salary	Ruby	Easy
1493	Longest Subarray of 1's After Deleting One Element	Ruby	Medium
1498	Number of Subsequences That Satisfy the Given Sum Condition	Ruby	Medium
1502	Can Make Arithmetic Progression From Sequence	Ruby	Easy
1503	Last Moment Before All Ants Fall Out of a Plank	Ruby	Medium
1508	Range Sum of Sorted Subarray Sums	Ruby	Medium
1514	Path with Maximum Probability	Ruby	Medium
1523	Count Odd Numbers in an Interval Range	Ruby	Easy
1535	Find the Winner of an Array Game	Ruby	Medium
1539	Kth Missing Positive Number	Ruby	Easy
1545	Find Kth Bit in Nth Binary String	Ruby	Medium
1547	Minimum Cost to Cut a Stick	Ruby	Hard
1557	Minimum Number of Vertices to Reach All Nodes	Ruby	Medium
1561	Maximum Number of Coins You Can Get	Ruby	Medium
1569	Number of Ways to Reorder Array to Get Same BST	Ruby	Hard
1572	Matrix Diagonal Sum	Ruby	Easy
1574	Shortest Subarray to be Removed to Make Array Sorted	Ruby	Medium
1575	Count All Possible Routes	Ruby	Hard
1579	Remove Max Number of Edges to Keep Graph Fully Traversable	Ruby	Hard
1584	Min Cost to Connect All Points	Ruby	Medium
1601	Maximum Number of Achievable Transfer Requests	Ruby	Hard
1603	Design Parking System	Ruby	Easy
1611	Minimum One Bit Operations to Make Integers Zero	Ruby	Hard
1615	Maximal Network Rank	Ruby	Medium
1630	Arithmetic Subarrays	Ruby	Medium
1631	Path With Minimum Effort	Ruby	Medium
1637	Widest Vertical Area Between Two Points Containing No Points	Ruby	Medium
1639	Number of Ways to Form a Target String Given a Dictionary	Ruby	Hard
1647	Minimum Deletions to Make Character Frequencies Unique	Ruby	Medium
1652	Defuse the Bomb	Ruby	Easy
1657	Determine if Two Strings Are Close	Ruby	Medium
1658	Minimum Operations to Reduce X to Zero	Ruby	Medium
1662	Check If Two String Arrays are Equivalent	Ruby	Easy
1671	Minimum Number of Removals to Make Mountain Array	Ruby	Hard
1675	Minimize Deviation in Array	Ruby	Hard
1679	Max Number of K-Sum Pairs	Ruby	Medium
1680	Concatenation of Consecutive Binary Numbers	Ruby	Medium
1685	Sum of Absolute Differences in a Sorted Array	Ruby	Medium
1688	Count of Matches in Tournament	Ruby	Easy
1697	Checking Existence of Edge Length Limited Paths	Ruby	Hard
1706	Where Will the Ball Fall	Ruby	Medium
1716	Calculate Money in Leetcode Bank	Ruby	Easy
1721	Swapping Nodes in a Linked List	Ruby	Medium
1727	Largest Submatrix With Rearrangements	Ruby	Medium
1732	Find the Highest Altitude	Ruby	Easy
1743	Restore the Array From Adjacent Pairs	Ruby	Medium
1751	Maximum Number of Events That Can Be Attended II	Ruby	Hard
1759	Count Number of Homogenous Substrings	Ruby	Medium
1768	Merge Strings Alternately	Ruby	Easy
1793	Maximum Score of a Good Subarray	Ruby	Hard
1799	Maximize Score After N Operations	Ruby	Hard
1802	Maximum Value at a Given Index in a Bounded Array	Ruby	Medium
1814	Count Nice Pairs in an Array	Ruby	Medium
1822	Sign of the Product of an Array	Ruby	Easy
1829	Maximum XOR for Each Query	Ruby	Medium
1838	Frequency of the Most Frequent Element	Ruby	Medium
1845	Seat Reservation Manager	Ruby	Medium
1846	Maximum Element After Decreasing and Rearranging	Ruby	Medium
1857	Largest Color Value in a Directed Graph	Ruby	Hard
1861	Rotating the Box	Ruby	Medium
1870	Minimum Speed to Arrive on Time	Ruby	Medium
1877	Minimize Maximum Pair Sum in Array	Ruby	Medium
1887	Minimize Maximum Pair Sum in Array	Ruby	Medium
1894	Find the Student that Will Replace the Chalk	Ruby	Medium
1903	Largest Odd Number in String	Ruby	Easy
1921	Eliminate Maximum Number of Monsters	Ruby	Medium
1926	Nearest Exit from Entrance in Maze	Ruby	Medium
1930	Unique Length-3 Palindromic Subsequences	Ruby	Medium
1964	Find the Longest Valid Obstacle Course at Each Position	Ruby	Hard
1970	Last Day Where You Can Still Cross	Ruby	Hard
1975	Maximum Matrix Sum	Ruby	Medium
1980	Find Unique Binary String	Ruby	Medium
2009	Minimum Number of Operations to Make Array Continuous	Ruby	Hard
2024	Maximize the Confusion of an Exam	Ruby	Medium
2044	Count Number of Maximum Bitwise-OR Subsets	Ruby	Medium
2050	Parallel Courses III	Ruby	Hard
2064	Minimized Maximum of Products Distributed to Any Store	Ruby	Medium
2070	Most Beautiful Item for Each Query	Ruby	Medium
2090	K Radius Subarray Averages	Ruby	Medium
2095	Delete the Middle Node of a Linked List	Ruby	Medium
2101	Detonate the Maximum Bombs	Ruby	Medium
2130	Maximum Twin Sum of a Linked List	Ruby	Medium
2131	Longest Palindrome by Concatenating Two Letter Words	Ruby	Medium
2140	Solving Questions With Brainpower	Ruby	Medium
2141	Maximum Running Time of N Computers	Ruby	Hard
2147	Number of Ways to Divide a Long Corridor	Ruby	Hard
2187	Minimum Time to Complete Trips	Ruby Python3	Medium
2215	Find the Difference of Two Arrays	Ruby	Easy
2218	Maximum Value of K Coins From Piles	Ruby	Hard
2251	Number of Flowers in Full Bloom	Ruby	Hard
2257	Count Unguarded Cells in the Grid	Ruby	Medium
2264	Largest 3-Same-Digit Number in String	Ruby	Easy
2265	Count Nodes Equal to Average of Subtree	Ruby	Medium
2272	Substring With Largest Variance	Ruby	Hard
2275	Largest Combination With Bitwise AND Greater Than Zero	Ruby	Medium
2300	Successful Pairs of Spells and Potions	Ruby	Medium
2305	Fair Distribution of Cookies	Ruby	Medium
2316	Count Unreachable Pairs of Nodes in an Undirected Graph	Ruby	Medium
2328	Number of Increasing Paths in a Grid	Ruby	Hard
2336	Smallest Number in Infinite Set	Ruby	Medium
2348	Number of Zero-Filled Subarrays	Ruby	Medium
2352	Equal Row and Column Pairs	Ruby	Medium
2353	Design a Food Rating System	Ruby	Medium
2360	Longest Cycle in a Graph	Ruby	Hard
2366	Minimum Replacements to Sort the Array	Ruby	Hard
2369	Check if There is a Valid Partition For The Array	Ruby	Medium
2390	Removing Stars From a String	Ruby	Medium
2391	Minimum Amount of Time to Collect Garbage	Ruby	Medium
2405	Count Days Spent Together	Ruby	Medium
2409	Count Days Spent Together	Ruby	Easy
2413	Smallest Even Multiple	Ruby	Easy
2433	Find The Original Array of Prefix Xor	Ruby	Medium
2439	Minimize Maximum of Array	Ruby	Medium
2444	Count Subarrays With Fixed Bounds	Ruby	Hard
2448	Minimum Cost to Make Array Equal	Ruby	Hard
2458	Height of Binary Tree After Subtree Removal Queries	Ruby	Hard
2461	Maximum Sum of Distinct Subarrays With Length K	Ruby	Medium
2462	Total Cost to Hire K Workers	Python3	Medium
2463	Minimum Total Distance Traveled	Ruby	Hard
2466	Count Ways To Build Good Strings	Ruby	Medium
2477	Minimum Fuel Cost to Report to the Capital	Ruby	Medium
2483	Minimum Penalty for a Shop	Ruby	Medium
2490	Circular Sentence	Ruby	Easy
2492	Minimum Score of a Path Between Two Cities	Ruby	Medium
2501	Longest Square Streak in an Array	Ruby	Medium
2516	Take K of Each Character From Left and Right	Ruby	Medium
2542	Maximum Subsequence Score	Ruby	Medium
2551	Put Marbles in Bags	Ruby	Hard
2563	Count the Number of Fair Pairs	Ruby	Medium
2583	Kth Largest Sum in a Binary Tree	Ruby	Medium
2595	Number of Even and Odd Bits	Ruby	Easy
2601	Prime Subtraction Operation	Ruby	Medium
2616	Minimize the Maximum Difference of Pairs	Ruby	Medium
2641	Cousins in Binary Tree II	Ruby	Medium
2642	Design Graph With Shortest Path Calculator	Ruby	Hard
2684	Maximum Number of Moves in a Grid	Ruby	Medium
2696	Minimum String Length After Removing Substrings	Ruby	Easy
2697	Lexicographically Smallest Palindrome	Ruby	Easy
2706	Buy Two Chocolates	Ruby	Easy
2707	Extra Characters in a String	Ruby	Medium
2742	Painting the Walls	Ruby	Hard
2785	Sort Vowels in a String	Ruby	Medium
2842	Difference Between Ones and Zeros in Row and Column	Ruby	Medium
2849	Determine if a Cell Is Reachable at a Given Time	Ruby	Medium
2924	Find Champion II	Ruby	Medium
2966	Divide Array Into Arrays With Max Difference	Ruby	Medium
3011	Find if Array Can Be Sorted	Ruby	Medium
3097	Shortest Subarray With OR At Least K II	Ruby	Medium
3163	String Compression III	Ruby	Medium
3243	Shortest Distance After Road Addition Queries I	Ruby	Medium
3254	Find the Power of K-Size Subarrays I	Ruby	Medium

Database

#	Title	Solution	Difficulty
175	Combine Two Tables	MySQL	Easy
181	Employees Earning More Than Their Managers	MySQL	Easy
182	Duplicate Emails	MySQL	Easy
183	Customers Who Never Order	MySQL	Easy
196	Delete Duplicate Emails	MySQL	Easy
197	Rising Temperature	MySQL	Easy
550	Game Play Analysis IV	MySQL	Medium
570	Managers with at Least 5 Direct Reports	MySQL	Medium
577	Employee Bonus	MySQL	Easy
584	Find Customer Referee	MySQL	Easy
595	Big Countries	MySQL	Easy
620	Not Boring Movies	MySQL	Easy
1068	Product Sales Analysis I	Ruby	Easy
1075	Project Employees I	Ruby	Easy
1148	Article Views I	MySQL	Easy
1174	Immediate Food Delivery II	MySQL	Medium
1193	Monthly Transactions I	MySQL	Medium
1211	Queries Quality and Percentage	MySQL	Easy
1251	Average Selling Price	MySQL	Easy
1280	Students and Examinations	MySQL	Easy
1378	Replace Employee ID With The Unique Identifier	MySQL	Easy
1581	Customer Who Visited but Did Not Make Any Transactions	MySQL	Easy
1633	Percentage of Users Attended a Contest	MySQL	Easy
1661	Average Time of Process per Machine	MySQL	Easy
1683	Invalid Tweets	MySQL	Easy
1757	Recyclable and Low Fat Products	MySQL	Easy
1934	Confirmation Rate	MySQL	Medium
2356	Confirmation Rate	MySQL	Easy

Shell

#	Title	Solution	Difficulty
192	Word Frequency	Shell	Medium
193	Valid Phone Numbers	Shell	Easy
194	Transpose File	Shell	Medium
195	Tenth Line	Shell	Easy