LeetCode solutions in Python and MySQL

About

This repository includes my solutions for all accepted submissions I made. They may not be the best approach to solve the problems. I wanted to keep them simple rather than looking for the optimal solution. Please note, that this project only contains non-premium problems.

For better readability I spit the list of problems into two separate parts. One for algorithms, the other for databases.

To search for a specific problem please use STRG + F to search for.

List of Problems

Algorithms

Number	Problem
1	Two Sums
2	Add Two Numbers
3	Longest Substring Without Repeating Characters
4	Median of Two Sorted Arrays
7	Reverse Integer
8	String to Integer (atoi)
9	Palindrome Number
11	Container With Most Water
12	Integer to Roman
13	Roman to Integer
14	Longest Common Prefix
15	3Sum
17	Letter Combinations of a Phone Number
18	4Sum
19	Remove Nth Node From End of List
20	Valid Parentheses
21	Merge Two Sorted Lists
22	Generate Parentheses
24	Swap Nodes in Pairs
26	Remove Duplicates From Sorted Array
27	Remove Element
28	Implement strStr
29	Divide Two Integers
34	Find First and Last Position of Element in Sorted Array
35	Search Insert Position
36	Valid Sudoku
37	Sudoku Solver
39	Combination Sum
41	First Missing Positive
42	Trapping Rain Water
43	Multiply Strings
46	Permutations
47	Permutations II
48	Rotate Image
49	Group Anagrams
50	Length of Last Word
53	Maximum Subarray
54	Spiral Matrix
56	Merge Intervals
59	Spiral Matrix II
66	Plus One
67	Add Binary
69	Sqrt(x)
70	Climbing Stairs
73	Set Matrix Zeroes
74	Search a 2D Matrix
75	Sort Colors
77	Combinations
78	Subsets
79	Word Search
83	Remove Duplicates from Sorted List
88	Merge Sorted Array
90	Subsets II
94	Binary Tree Inorder Traversal
98	Validate Binary Search Tree
100	Same Tree
101	Symmetric Tree
104	Maximum Depth of Binary Tree
108	Convert Sorted Array to Binary Search Tree
109	Convert Sorted List to Binary Search Tree
110	Balanced Binary Tree
111	Minimum Depth of Binary Tree
112	Path Sum
118	Pascal´s Triangle
119	Pascal´s Triangle II
121	Best Time to Buy and Sell Stock
125	Valid Palindrome
129	Sum Root to Leaf Numbers
130	Surrounded Regions
136	Single Number
137	Single Number 2
141	Linked List Cycle
144	Binary Tree Preorder Traversal
145	Binary Tree Postorder Traversal
146	LRU Cache
151	Reverse Words in a String
155	Min Stack
160	Intersection of Two Linked Lists
162	Find Peak Element
167	Two Sum II - Input Array is Sorted
168	Excel Sheet Column Title
169	Majority Element
171	Excel Sheet Column Number
172	Factorial Trailing Zeroes
187	Repeated DNA Sequences
189	Rotate Array
190	Reverse Bits
191	Number of 1 Bits
200	Number of Islands
201	Bitwise AND of Numbers Range
202	Happy Number
203	Remove Linked List Elements
204	Count Primes
205	Isomorphic Strings
206	Reverse Linked List
215	Kth Largest Element in an Array
217	Contains Duplicate
219	Contains Duplicates II
222	Count Complete Tree Nodes
223	Rectangle Area
225	Implement Stack Using Queues
226	Invert Binary Tree
228	Summary Ranges
229	Majority Element II
230	Kth Smallest Element in a BST
231	Power of Two
232	Implement Queue using Stacks
234	Palindrome Linked List
238	Product of Array Except Self
242	Valid Anagram
257	Binary Tree Paths
258	Add Digits
260	Single Number 3
263	Ugly Number
268	Missing Number
274	H-Index
278	First Bad Version
283	Move Zeros
284	Peeking Iterator
287	Find the Duplicate Number
290	Word Pattern
292	Nim Game
295	Find Median from Data Stream
303	Range Sum Query - Immutable
319	Bulb Switcher
326	Power of Three
338	Counting Bits
342	Power of Four
344	Reverse String
345	Reverse Vowels of a String
347	Top K Frequent Elements
349	Intersection of Two Arrays
350	Intersection of Two Arrays II
367	Valid Perfect Square
371	Sum of Two Integers
374	Guess Number Higher or Lower
378	Kth Smallest Element in a Sorted Matrix
383	Ransom Note
384	Shuffle an Array
386	Lexicographical Numbers
387	First Unique Character in a String
389	Find the Difference
392	Is Subsequence
397	Integer Replacement
404	Sum of Left Leaves
405	Convert a Number to Hexadecimal
409	Longest Palindrome
412	Fizz Buzz
414	Third Maximum Number
415	Add Strings
419	Battleship in a Board
434	Number of Segments in a String
441	Arranging Coins
442	Find all Duplicates in an Array
448	Find All Numbers Disappeared in an Array
451	Sort Characters by Frequency
455	Assign Cookies
459	Repeated Substring Pattern
461	Hamming Distance
463	Island Perimeter
476	Number Complement
478	Generate Random Point in a Circle
482	License Key Formatting
485	Max Consecutive Ones
492	Construct the Rectangle
495	Teemo Attacking
496	Next Greater Element I
500	Keyboard Row
501	Find Mode in Binary Search Tree
504	Base 7
506	Relative Ranks
507	Perfect Number
509	Fibonacci Number
515	Find Largest Value in Each Tree Row
520	Detect Capital
521	Longest Uncommon Subsequence I
530	Minimum Absolute Difference in BST
535	Encode and Decode TinyURL
540	Single Element in a Sorted Array
541	Reverse String II
543	Diameter of Binary Tree
551	Student Attendance Record I
557	Reverse Words in a String III
559	Maximum Depth of N-ary Tree
561	Array Partition
563	Binary Tree Tilt
566	Reshape the Matrix
572	Subtree of Another Tree
575	Distribute Candies
589	N-Ary Tree Preorder Traversal
590	N-Ary Tree Postorder Traversal
593	Valid Square
594	Longest Harmonious Subsequence
598	Range Addition II
599	Minimum Index Sum of Two Lists
605	Can Place Flowers
617	Merge Two Binary Trees
628	Maximum Product of Three Numbers
633	Sum of Square Numbers
637	Average of Levels in Binary Tree
643	Maximum Average Subarray I
645	Set Missmatch
648	Replace Words
653	Two Sums IV - Input is a BST
654	Maximum Binary Tree
657	Robot Return to Origin
661	Image Smoother
665	Non-decreasing Array
671	Second Minimum Node in a Binary Tree
674	Longest Continuous Increasing Subsequence
680	Valid Palindrome II
682	Baseball Game
692	Top K Frequent Words
693	Binary Number with Alternating Bits
695	Max Area of Island
700	Search in a Binary Search Tree
701	Insert into a Binary Search Tree
703	Kth Largest Element in a Stream
704	Binary Search
705	Design HashSet
706	Design HashMap
709	To Lower Case
717	1-bit and 2-bit Characters
724	Find Pivot Index
728	Self Dividing Numbers
729	My Calendar I
735	Asteroid Collision
744	Find Smallest Letter Greater Than Target
746	Min Cost Climbing Stairs
747	Largest Number at Least Twice of Others
748	Shortest Completing Word
762	Prime Number of Set Bits in Binary Representation
766	Toeplitz Matrix
771	Jewels and Stones
783	Minimum Distance Between BST Nodes
784	Letter Case Permutation
788	Rotated Digits
796	Rotate String
804	Unique Morse Code Words
806	Number of Lines To Write String
812	Largest Triangle Area
814	Binary Tree Pruning
819	Most Common Word
821	Shortest Distance to a Character
824	Goat Latin
830	Positions of Large Groups
832	Flipping an Image
836	Rectangle Overlap
844	Backspace String Compare
852	Peak Index in a Mountain Array
859	Buddy Strings
860	Lemonade Change
867	Transpose Matrix
868	Binary Gap
872	Leaf Similar Trees
873	Length of Longest Fibonacci Subsequence
876	Middle of the Linked List
877	Stone Game
881	Boats to Save People
883	Projection Area of 3D Shapes
884	Uncommon Words from Two Sentences
888	Fair Candy Swap
890	Find and Replace Pattern
892	Surface Area of 3D Shapes
896	Monotonic Array
905	Sort Array By Parity
908	Smallest Range I
912	Sort an Array
914	X of a Kind in a Deck of Cards
917	Reverse Only Letters
921	Minimum Add to Make Parentheses Valid
922	Sort Array By Parity II
925	Long Pressed Name
929	Unique Email Addresses
933	Number of Recent Calls
938	Range Sum of BST
941	Valid Mountain Array
942	DI String Match
944	Delete Column to Make Sorted
946	Validate Stack Sequences
949	Largest Time for Given Digits
961	N-Repeated Element in Size 2N Array
965	Univalued Binary Tree
973	K Closest Points to Origin
976	Largest Perimeter Triangle
977	Squares of a Sorted Array
985	Sum of Even Numbers After Queries
989	Add to Array-Form of Integer
997	Find the Town Judge
999	Available Captures for Rook
1002	Find Common Characters
1005	Maximize Sum Of Array After K Negations
1009	Complement of Base 10 Integer
1010	Pairs of Songs With Total Durations Divisible by 60
1013	Partition Array Into Three Parts With Equal Sum
1018	Binary Prefix Divisible By 5
1021	Remove Outermost Parentheses
1022	Sum of Root To Leaf Binary Numbers
1025	Divisor Game
1030	Matrix Cells in Distance Order
1037	Valid Boomerang
1038	Binary Search Tree to Greater Sum Tree
1046	Last Stone Weight
1047	Remove All Adjacent Duplicates In String
1051	Height Checker
1071	Greatest Common Divisor of Strings
1078	Occurrences After Bigram
1079	Letter Tile Possibilities
1089	Duplicate Zeros
1103	Distribute Candies to People
1108	Defanging an IP Address
1122	Relative Sort Array
1128	Number of Equivalent Domino Pairs
1137	N-th Tribonacci Number
1146	Snapshot Array
1154	Day of the Year
1155	Number of Dice Rolls With Target Sum
1160	Find Words That Can Be Formed by Characters
1184	Distance Between Bus Stops
1185	Day of the Week
1189	Maximum Number of Balloons
1200	Minimum Absolute Difference
1207	Unique Number of Occurrences
1217	Minimum Costs to Move Chips to The Same Position
1221	Split a String in Balanced Strings
1232	Check If It Is a Straight Line
1252	Cells with Odd Values in a Matrix
1260	Shift 2D Grid
1266	Minimum Time Visiting All Points
1275	Find Winner on a Tic Tac Toe Game
1276	Number of Burgers with No Waste of Ingredients
1281	Substract the Product and Sum of Digits of an Integer
1286	Iterator for Combination
1287	Element Appearing More Than 25% in Sorted Array
1288	Remove Covered Intervals
1290	Convert Binary Number in a Linked List to Integer
1295	Find Numbers with Even Number of Digits
1299	Replace Element with Greatest Element on Right Side
1302	Deepest Leaves Sum
1304	Find N Unique Integers Sum up to Zero
1305	All Elements in Two Binary Search Trees
1309	Decrypt String from Alphabet to Integer Mapping
1313	Decompress Run-Length Encoded List
1315	Sum of Nodes with Even-Valued Grandparent
1317	Convert Integer to the Sum of Two No-Zero Integers
1324	Print Words Vertically
1360	Number of Days Between Two Dates
1323	Maximum 69 Number
1331	Rank Transform of an Array
1332	Remove Palindromic Subsequences
1337	The K Weakest Rows in a Matrix
1338	Reduce Array Size to The Half
1344	Angle Between Hands of a Clock
1346	Check if N and its Double Exists
1347	Minimum Number of Steps to Make Two Strings Anagram
1351	Count Negative Numbers in a Sorted Matrix
1356	Sort Integers by The Number of 1 Bits
1357	Apply Discount every n Orders
1365	How Many Numbers Are Smaller Than the Current Number
1366	Rank Teams by Votes
1370	Increasing Decreasing String
1374	Generate a String With Characters That Have Odd Counts
1379	Find a Corresponding Node of a Binary Tree in a Clone of That Tree
1380	Lucky Numbers in a Matrix
1381	Design a Stack With Increment Operation
1385	Find the Distance Value Between Two Arrays
1387	Sort Integers by The Power Value
1389	Create Target Array in the Given Order
1390	Four Divisors
1394	Find Lucky Integer in an Array
1399	Count Largest Group
1401	Circle and Rectangle Overlapping
1403	Minimum Subsequence in Non-Increasing Order
1408	String Matching in an Array
1409	Queries on a Permutation With Key
1410	HTML Entity Parser
1413	Minimum Value to Get Positive Step by Step Sum
1414	Find the Minimum Number of Fibonacci Numbers Whose Sum is K
1417	Reformat The String
1422	Maximum Score After Splitting a String
1431	Kids With the Greatest Number of Candies
1432	Number of Steps to Reduce a Number to Zero
1436	Destination City
1437	Check If All 1´s Are at Least Length K Places Away
1446	Consecutive Characters
1450	Number of Students Doing Homework at a Given Time
1451	Rearrange Words in a Sentence
1455	Check If a Word Occurs As a Prefix of Any Word in a Sentence
1460	Make Two Arrays Equal by Reversing Subarrays
1464	Maximum Product of Two Elements in an Array
1470	Shuffle the Array
1472	Design Browser History
1475	Final Prices With a Special Discount in a Shop
1476	Subrectangle Queries
1480	Running Sum of 1d Array
1481	Least Number of Unique Integers after K Removals
1486	XOR Operation in an Array
1491	Average Salary Excluding the Minimum and Maximum Salary
1492	The kth Factor of n
1496	Path Crossing
1502	Can Make Arithmetic Progression From Sequence
1507	Reformat Date
1512	Number of Good Pairs
1518	Water Bottles
1523	Count Odd Numbers in an Interval Range
1528	Shuffle String
1534	Count Good Triplets
1539	Kth Missing Positive Number
1544	Make The String Great
1550	Three Consecutive Odds
1551	Minimum Operations to Make Array Equal
1556	Thousand Separator
1561	Maximum Number of Coins You Can Get
1566	Detect Pattern of Length M Repeated K or More Times
1572	Matrix Diagonal Sum
1576	Replace All ?´s to Avoid Consecutive Repeating Characters
1582	Special Positions in a Binary Matrix
1588	Sum of All Odd Length Subarrays
1592	Rearrange Spaces Between Words
1603	Design Parking System
1605	Find Valid Matrix Given Row and Column Sums
1608	Special Array With X Elements Greater Than or Equal X
1614	Maximum Nesting Depth of the Parentheses
1619	Mean of Array After Removing Some Elements
1624	Largest Substring Between Two Equal Characters
1629	Slowest Key
1630	Arithmetic Subarrays
1636	Sort Array by Increasing Frequency
1637	Widest Vertical Area Between Two Points Containing No Points
1640	Check Array Formation Through Concatenation
1647	Minimum Deletions to Make Character Frequencies Unique
1652	Defuse the Bomb
1656	Design an Ordered Stream
1662	Check If Two String Arrays are Equivalent
1668	Maximum Repeating Substring
1672	Richest Customer Wealth
1678	Goal Parser Interpretation
1684	Count the Number of Consistent Strings
1688	Count of Matches in Tournament
1689	Partitioning Into Minimum Number of Deci-Binary Numbers
1694	Reformat Phone Number
1700	Number of Students Unable to Eat Lunch
1704	Determine if String Halves are Alike
1710	Maximum Units on a Truck
1716	Calculate Money in Leetcode Bank
1720	Decode XORed Array
1725	Number Of Rectangles That Can Form The Largest Square
1732	Find the Highest Altitude
1736	Latest Time by Replacing Hidden Digits
1742	Maximum Number of Balls in a Box
1748	Sum of Unique Elements
1752	Check if Array is Sorted and Rotated
1753	Maximum Score From Removing Stones
1758	Minimum Changes to Make Alternating Binary String
1763	Longest Nice Substring
1768	Merge Strings Alternately
1769	Minimum Number of Operations to Move All Balls to Each Box
1773	Count Items Matching a Rule
1779	Find Nearest Point That Has the Same X or Y Coordinate
1784	Check if Binary String Has at Most One Segment of Ones
1790	Check if One String Swap Can Make Strings Equal
1791	Find Center of Star Graph
1796	Second Largest Digit in String
1800	Maximum Ascending Subarray Sum
1805	Number of Different Integers in a String
1812	Determine Color of a Chessboard Square
1816	Truncate Sentence
1817	Finding the Users Active Minutes
1822	Sign of the Product of an Array
1823	Find the Winner of the Circular Game
1827	Minimum Operations to Make the Array Increasing
1828	Queries on Number of Points Inside a Circle
1832	Check if Sentence is Pangram
1833	Maximum Ice Cream Bars
1837	Sum of Digits in Base K
1844	Replace All Digits with Characters
1845	Seat Reservation Manager
1848	Minimum Distance to the Target Element
1859	Sorting the Sentence
1860	Incremental Memory Leak
1863	Sum of All Subset XOR Totals
1869	1869_longer_contiguous_segments_of_ones_than_zeros
1876	Substrings of Size Three with Distinct Characters
1880	Check if Word Equals Summation of Two Words
1886	Determine Wheather Matrix Can Be Obtained By Rotation
1887	Reduction Operations to Make the Array Elements Equal
1893	Check if All the Integers in a Range Are Covered
1898	Redistribute Characters to Make All Strings Equal
1903	Largest Odd Number in String
1909	Remove One Element to Make the Array Strictly Increasing
1910	Remove All Occurrences of a String
1913	Maximum Product Difference Between Two Pairs
1920	Build Array from Permutation
1925	Count Square Sum Triples
1929	Concatenation of Array
1935	Maximum Number of Words You Can Type
1941	Check if All Characters have Equal Numnber of Occurrences
1945	Sum of Digits of String After Convert
1952	Three Divisors
1957	Delete Character to Make Fancy String
1961	Check If String Is a Prefix of Array
1962	Remove Stones to Minimize the Total
1967	Number of Strings That Appear as Substrings in Word
1974	Minimum Time to Type Word Using Special Typewriter
1979	Find Greatest Common Divisor of Array
1984	Minimum Difference Between Highest and Lowest of K Scores
1991	Find the Middle Index in Array
1995	Count Special Quadruplets
2000	Reverse Prefix of Word
2006	Count Number of Pairs With Absolute Difference K
2011	Final Value of Variable After Performing Operations
2016	Maximum Difference Between Increasing Elements
2022	Convert 1D Array Into 2D Array
2023	Number of Pairs of Strings With Concatenation Equal to Target
2027	Minimum Moves to Convert String
2032	Two Out of Three
2037	Minimum Number of Moves to Seat Everyone
2042	Check if Numbers Are Ascending in a Sentence
2043	Simple Bank System
2047	Number of Valid Words in a Sentence
2053	Kth Distinct String in an Array
2057	Smallest Index With Equal Value
2062	Count Vowel Substrings of a String
2068	Check Whether Two Strings are Almost Equivalent
2073	Time Needed to Buy Tickets
2078	Two Furthest Houses With Different Colors
2085	Count Common Words With One Occurence
2089	Find Target Indices After Sorting Array
2094	Finding 3-Digit Even Numbers
2095	Delete the Middle Node of a Linked List
2099	Find Subsequence of Length K With the Largest Sum
2103	Rings and Rods
2108	Find First Palindromic String in the Array
2109	Adding Spaces to a String
2114	Maximum Number of Words Found in Sentence
2119	A Number After a Double Reversal
2124	Check if All As Appears Before All Bs
2129	Capitalize the Title
2133	Check if Every Row and Column Contains All Numbers
2138	Divide a String Into Groups of Size k
2144	Minimum Cost of Buying Candies With Discount
2148	Count Elements With Strictly Smaller and Greater Elements
2149	Rearrange Array Elements by Sign
2150	Find All Lonely Numbers in the Array
2154	Keep Multiplying Found Vales by Two
2160	Minimum Sum of Four Digit Number After Splitting Digits
2161	Partition Array According to Given Pivot
2164	Sort Even and Odd Indices Independently
2165	Smallest Value of the Rearranged Number
2169	Count Operations to Obtain Zero
2176	Count Equal and Divisible Pairs in an Array
2177	Find Three Consecutive Integers That Sum to a Given Number
2180	Count Integers With Even Digit Sum
2181	Merge Nodes in Between Zeros
2185	Counting Words With a Given Prefix
2190	Most Frequent Number Following Key In an Array
2194	Cells in a Range on an Excel Sheet
2200	Find All K-Distant Indices in an Array
2206	Divide Array Into Equal Pairs
2210	Count Hills and Valleys in an Array
2215	Find the Difference of Two Arrays
2220	Minimum Bit Flips to Convert Number
2221	Find Triangular Sum of an Array
2224	Minimum Number of Operations to Convert Time
2225	Find Players With Zero or One Losses
2231	Largest Number After Digit Swaps by Parity
2235	Add Two Integers
2236	Root Equals Sum of Children
2239	Find Closest Number to Zero
2241	Design an ATM Machine
2243	Calculate Digit Sum of a String
2244	Minimum Rounds to Complete All Tasks
2248	Intersection of Multiple Arrays
2249	Count Lattice Points Inside a Circle
2255	Count Prefixes of a Given String
2259	Remove Digit From Number to Maximize Result
2264	Largest 3-Same-Digit Number in String
2269	Find the K-Beauty of a Number
2273	Find Resultant Array After Removing Anagrams
2278	Percentage of Letter in String
2279	Maximum Bags With Full Capacity of Rocks
2283	Check if Number Has Equal Digit Count and Digit Value
2284	Sender With Largest Word Count
2287	Rearrange Characters to Make Target String
2288	Apply Discount to Prices
2293	Min Max Game
2295	Replace Elements in an Array
2299	Strong Password Checker II
2303	Calculate Amount Paid in Taxes
2309	Greatest English Letter in Upper and Lower Case
2315	Count Asterisks
2319	Check if Matrix is X-Matrix
2325	Decode the Message
2331	Evaluate Boolean Binary Tree
2335	Minimum Amount of Time to Fill Cups
2336	Smallest Number in Infite Set
2341	Maximum Number of Pairs in Array
2347	Best Poker Hand
2351	First Letter to Appear Twice
2352	Equal Row and Column Pairs
2353	Design a Food Rating System
2357	Make Array Zero By Subtracting Equal Amounts
2363	Merge Similar Items
2367	Number of Arithmetic Triplets
2373	Largest Local Value in a Matrix
2379	Minimum Recolors to Get K Consecutive Black Blocks
2383	Minimum Hours of Training to Win a Competition
2389	Longest Subsequence With Limited Sum
2390	Remove Stars From a String
2395	Find Subarrays With Equal Sum
2396	Strictly Palindromic Number
2399	Check Distances Between Same Letters
2404	Most Frequent Even Element
2405	Optimal Partition of String
2409	Count Days Spent Together
2410	Maximum_matching_of_players_with_trainers
2413	Smallest Even Multiple
2414	Length of the Longest Alphabetical Continuous Substring
2418	Sort the People
2423	Remove Letter To Equalize Frequency
2427	Number of Common Factors
2428	Maximum Sum of an Hourglass
2432	The Employee That Worked on the Longest Task
2433	Find The Original Array of Prefix Xor
2437	Number of Valid Clock Times
2441	Largest Positive Integer That Exists With Its Negative
2442	Count Number of Distinct Integers After Reverse Operations
2446	Determine if Two Events Have Conflict
2451	Odd String Difference
2452	Words Within Two Edits of Dictionary
2455	Average Value of Even Numbers That Are Divisible by Three
2460	Apply Operations to an Array
2465	Number of Distinct Averages
2469	Convert the Temperature
2475	Number of Unequal Triplets in Array
2482	Difference Between Ones and Zeros in Row and Column
2485	Find the Pivot Integer
2481	Minimum Cuts to Divide a Circle
2490	Circular Sentence
2491	Divide Players Into Teams of Equal Skill
2496	Maximum Value of a String in an Array
2500	Delete Greatest Value in Each Row
2506	Count Pairs of Similar Strings
2515	Shortest Distance to Target String in a Circular Array
2520	Count the Digits That Divide a Number
2525	Categorize Box According to Criteria
2529	Maximum Count of Positive Integer and Negative Integer
2530	Maximum Score After Applying K Operations
2535	Difference Between Element Sum and Digit Sum of an Array
2540	Minimum Common Value
2544	Alternating Digit Sum
2545	Sort the Students by Their Kth Score
2549	Count Distinct Numbers on Board
2553	Separate the Digits in an Array
2554	Maximum Number of Integers to Choose From a Range I
2558	Take Gifts From the Richest Pile
2559	Count Vowel Strings in Ranges
2562	Find the Array Concatenation Value
2566	Maximum Difference by Remapping a Digit
2570	Merge Two 2D Arrays by Summing Values
2574	Left and Right Sum Differences
2578	Split With Minimum Sum
2579	Count Total Number of Colored Cells
2586	Count the Number of Vowel Strings in Range
2593	Find Score of an Array After Marking All Elements
2595	Number of Even and Odd Bits
2600	K Items With the Maximum Sum
2605	Form Smallest Number From Two Digit Arrays
2609	Find the Longest Balanced Substring of a Binary String
2610	Convert an Array Into a 2D Array With Conditions
2614	Prime in Diagonal
2639	Find the Width of Columns of a Grid
2643	Row With Maximum Ones
2644	Find the Maximum Divisibility Score
2651	Calculate Delayed Arrival Time
2652	Sum Multiples
2656	Maximum Sum With Exactly K Elements
2657	Find the Prefix Common Array of Two Arrays
2658	Maximum Number of Fish in a Grid
2660	Determine the Winner of a Bowling Game
2670	Find the Distinct Difference Array
2678	Number of Senior Citizens
2679	Sum in a Matrix
2696	Minimum String Length After Removing Substrings
2697	Lexicographically Smallest Palindrome
2706	Buy Two Chocolates
2710	Remove Trailing Zeros From a String
2716	Minimize String Length
2717	Semi-Ordered Permutation
2729	Check if The Number is Fascinating
2733	Neither Minimum nor Maximum
2739	Total Distance Traveled
2740	Find the Value of the Partition
2744	Find Maximum Number of String Pairs
2748	Number of Beautiful Pairs
2760	Longest Even Odd Subarray With Threshold
2761	Prime Pairs With Target Sum
2765	Longest Alternating Subarray
2769	Find the Maximum Achievable Number
2778	Sum of Squares of Special Elements
2784	Check if Array is Good
2785	Sort Vowels in a String
2788	Split Strings by Separator
2798	Number of Employees Who Met the Target
2799	Count Complete Subarrays in an Array
2807	Insert Greatest Common Divisors in Linked List
2810	Faulty Keyboard
2815	Max Pair Sum in an Array
2824	Count Pairs Whose Sum is Less than Target
2828	Check if a String is an Acronym of Words
2833	Furthest Point From Origin
2843	Count Symmetric Integers
2848	Points That Intersect With Cars
2856	Minimum Array Length After Pair Removals
2859	Sum of Values at Indices With K Set Bits
2864	Maximum Odd Binary Number
2869	Minimum Operations to Collect Elements
2873	Maximum Value of an Ordered Triplet I
2894	Divisible and Non-divisible Sums Difference
2899	Last Visited Integers
2903	Find Indices With Index and Value Difference I
2908	Minimum Sum of Mountain Triplets I
2913	Subarrays Distinct Element Sum of Squares I
2928	Distribute Candies Among Children I
2932	Maximum Strong Pair XOR I
2937	Make Three Strings Equal
2942	Find Words Containing Character
2946	Matrix Similarity After Cyclic Shifts
2956	Find Common Elements Between Two Arrays
2974	Minimum Number Game
2965	Find Missing and Repeated Values
2980	Check if Bitwise OR Has Trailing Zeros
3000	Maximum Area of Longest Diagonal Rectangle
3005	Count Elements With Maximum Frequency

Pandas

Number	Problem
177	Nth Highest Salary
180	Consecutive Numbers
183	Customers Who Never Order
185	Department Top Three Salaries
197	Rising Temperature
550	Game Play Analysis IV
570	Managers with at least 5 direct reports
577	Employee Bonus
585	Investments in 2016
602	Friend Requests II: Who Has the Most Friends
610	Triangle Judgement
619	Biggest Single Number
626	Exchange Seats
1045	Customers who bought all Products
1070	Product Sales Analysis III
1075	Project Employees I
1174	Immediate Food Delivery II
1193	Monthly Transactions I
1204	Last Person to Fit in the Bus
1211	Queries Quality and Percentage
1280	Students and Examinations
1321	Restaurant Growth
1341	Movie Rating
1366	Percentage of Users Attended a Contest
1378	Replace Employee ID With The Unique Identifier
1517	Find Users With Valid E-Mails
1581	Customer Who Visited but Did Not Make Any Transactions
1661	Average Time of Process per Machine
1731	The Number of Employees Which Report to Each Employee
1907	Count Salary Categories
1934	Confirmation Rate
2877	Create a DataFrame from List
2878	Get the Size of a Dataframe
2879	Display the First Three Rows
2881	Create a New Column
2882	Drop Duplicate Rows
2880	Select Data
2881	Create a New Column
2883	Drop Missing Data
2884	Modify Columns
2885	Rename Columns
2886	Change Data Type
2887	Fill Missing Data
2888	Reshape Data: Concatenate
2889	Reshape Data: Pivot
2890	Reshape Data: Melt
2891	Method Chaining

Databases

Number	Problem
169	Delete Duplicate Emails
175	Combine Two Tables
176	Second Highest Salary
181	Rank Scores
182	Employee Earning More Than Their Managers
184	Duplicate Emails
511	Department Highest Salary
584	Game Play Analysis I
586	Find Customer Referee
595	Customer Placing the Largest Number of Orders
595	Big Countries
596	Classes More Tan 5 Students
607	Sales Person
620	Not Boring Movies
627	Swap Salary
1050	Actors and Directors Who Cooperated At Least Three Times
1068	Product Sales Analysis I
1141	User Activity for the Past 30 Days I
1148	Article Views I
1251	Average Selling Price
1327	List the Products Ordered in a Period
1407	Top Travellers
1484	Group Sold Products By The Date
1527	Patients With a Condition
1587	Bank Accounts Summary II
1667	Fix Names in a Table
1683	Invalid Tweets
1693	Daily Leads and Partners
1729	Find Follower Count
1741	Find Total Time Spend by Each Employee
1757	Recyclable and Low Fat Products
1789	Primary Department for Each Employee
1795	Rearrange Products Table
1872	Calculate Special Bonus
1890	The Latest Login in 202
1965	Employee With Missing Information
1978	Employees Whose Manager Left the Company
2356	Number of Unique Subjects Taught by Each Teacher

Bash

Number	Problem
193	Valid Phone Numbers
195	Tenth Line