LeetCode Database Solution List
This is a list of LeetCode database problems and solutions. All problems and solutions are listed by difficulty levels.
Easy Problems
| No. | Problem | Difficulty | Solution | |||
|---|---|---|---|---|---|---|
| 175 | Combine Two Tables | Easy |
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| 176 | Second Highest Salary | Easy |
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| 181 | Employees Earning More Than Their Managers | Easy |
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| 182 | Duplicate Emails | Easy |
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| 183 | Customers Who Never Order | Easy |
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| 196 | Delete Duplicate Emails | Easy |
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| 197 | Rising Temperature | Easy |
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| 511 | Game Play Analysis I | Easy |
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| 512 | Game Play Analysis II | Easy |
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| 577 | Employee Bonus | Easy |
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| 584 | Find Customer Referee | Easy |
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| 586 | Customer Placing The Largest Number Of Orders | Easy |
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| 595 | Big Countries | Easy |
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| 596 | Classes More Than 5 Students | Easy |
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| 597 | Friend Requests I: Overall Acceptance Rate | Easy |
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| 603 | Consecutive Available Seats | Easy |
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| 607 | Sales Person | Easy |
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| 610 | Triangle Judgement | Easy |
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| 613 | Shortest Distance In A Line | Easy |
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| 619 | Biggest Single Number | Easy |
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| 620 | Not Boring Movies | Easy |
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| 627 | Swap Salary | Easy |
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| 1050 | Actors And Directors Who Cooperated At Least Three Times | Easy |
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| 1068 | Product Sales Analysis I | Easy |
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| 1069 | Product Sales Analysis II | Easy |
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| 1075 | Project Employees I | Easy |
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| 1076 | Project Employees II | Easy |
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| 1082 | Sales Analysis I | Easy |
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| 1083 | Sales Analysis II | Easy |
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| 1084 | Sales Analysis III | Easy |
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| 1113 | Reported Posts | Easy |
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| 1141 | User Activity For The Past 30 Days I | Easy |
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| 1142 | User Activity For The Past 30 Days II | Easy |
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| 1148 | Article Views I | Easy |
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| 1173 | Immediate Food Delivery I | Easy |
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| 1179 | Reformat Department Table | Easy |
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| 1211 | Queries Quality And Percentage | Easy |
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| 1241 | Number Of Comments Per Post | Easy |
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| 1251 | Average Selling Price | Easy |
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| 1280 | Students And Examinations | Easy |
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| 1294 | Weather Type In Each Country | Easy |
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| 1303 | Find The Team Size | Easy |
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| 1322 | Ads Performance | Easy |
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| 1327 | List The Products Ordered In A Period | Easy |
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| 1350 | Students With Invalid Departments | Easy |
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| 1378 | Replace Employee ID With The Unique Identifier | Easy |
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| 1407 | Top Travellers | Easy |
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| 1435 | Create A Session Bar Chart | Easy |
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| 1484 | Group Sold Products By The Date | Easy |
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| 1495 | Friendly Movies Streamed Last Month | Easy |
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| 1511 | Customer Order Frequency | Easy |
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| 1517 | Find Users With Valid Emails | Easy |
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| 1527 | Patients With A Condition | Easy |
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| 1543 | Fix Product Name Format | Easy |
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| 1565 | Unique Orders And Customers Per Month | Easy |
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| 1571 | Warehouse Manager | Easy |
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| 1581 | Customer Who Visited But Did Not Make Any Transactions | Easy |
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| 1587 | Bank Account Summary II | Easy |
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| 1607 | Sellers With No Sales | Easy |
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| 1623 | All Valid Triplets That Can Represent A Country | Easy |
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| 1633 | Percentage Of Users Attended A Contest | Easy |
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| 1661 | Average Time Of Process Per Machine | Easy |
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| 1667 | Fix Names In A Table | Easy |
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| 1677 | Product’s Worth Over Invoices | Easy |
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| 1683 | Invalid Tweets | Easy |
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| 1693 | Daily Leads And Partners | Easy |
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| 1729 | Find Followers Count | Easy |
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| 1731 | The Number Of Employees Which Report To Each Employee | Easy |
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| 1741 | Find Total Time Spent By Each Employee | Easy |
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| 1757 | Recyclable And Low Fat Products | Easy |
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| 1777 | Product’s Price For Each Store | Easy |
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| 1789 | Primary Department For Each Employee | Easy |
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| 1795 | Rearrange Products Table | Easy |
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| 1809 | Ad-Free Sessions Table | Easy |
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| 1821 | Find Customers With Positive Revenue this Year | Easy |
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| 1853 | Convert Date Format | Easy |
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| 1873 | Calculate Special Bonus | Easy |
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| 1890 | The Latest Login in 2020 | Easy |
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| 1939 | Users That Actively Request Confirmation Messages | Easy |
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| 1965 | Employees With Missing Information | Easy |
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| 1978 | Employees Whose Manager Left the Company | Easy |
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Medium Problems
| No. | Problem | Difficulty | Solution | |||
|---|---|---|---|---|---|---|
| 177 | Nth Highest Salary | Medium |
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| 178 | Rank Scores | Medium |
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| 180 | Consecutive Numbers | Medium |
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| 184 | Department Highest Salary | Medium |
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| 534 | Game Play Analysis III | Medium |
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| 550 | Game Play Analysis IV | Medium |
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| 570 | Managers With At Least 5 Direct Reports | Medium |
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| 574 | Winning Candidate | Medium |
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| 578 | Get Highest Answer Rate Question | Medium |
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| 580 | Count Student Number In Departments | Medium |
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| 585 | Investments In 2016 | Medium |
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| 602 | Friend Requests II: Who Has The Most Friends | Medium |
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| 608 | Tree Node | Medium |
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| 612 | Shortest Distance In A Plane | Medium |
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| 614 | Second Degree Follower | Medium |
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| 626 | Exchange Seats | Medium |
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| 1045 | Customers Who Bought All Products | Medium |
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| 1070 | Product Sales Analysis III | Medium |
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| 1077 | Project Employees III | Medium |
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| 1098 | Unpopular Books | Medium |
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| 1107 | New Users Daily Count | Medium |
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| 1112 | Highest Grade For Each Student | Medium |
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| 1126 | Active Business | Medium |
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| 1132 | Reported Posts II | Medium |
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| 1149 | Article Views II | Medium |
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| 1158 | Market Analysis I | Medium |
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| 1164 | Product Price At A Given Date | Medium |
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| 1174 | Immediate Food Delivery II | Medium |
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| 1193 | Monthly Transactions I | Medium |
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| 1204 | Last Person To Fit In The Elevator | Medium |
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| 1205 | Monthly Transactions II | Medium |
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| 1212 | Team Scores In Football Tournament | Medium |
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| 1264 | Page Recommendations | Medium |
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| 1270 | All People Report To The Given Manager | Medium |
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| 1285 | Find The Start And End Number Of Continuous Ranges | Medium |
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| 1308 | Running Total For Different Genders | Medium |
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| 1321 | Restaurant Growth | Medium |
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| 1341 | Movie Rating | Medium |
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| 1355 | Activity Participants | Medium |
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| 1364 | Number Of Trusted Contacts Of A Customer | Medium |
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| 1393 | Capital Gain/Loss | Medium |
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| 1398 | Customers Who Bought Products A And B But Not C | Medium |
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| 1421 | NPV Queries | Medium |
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| 1440 | Evaluate Boolean Expression | Medium |
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| 1445 | Apples & Oranges | Medium |
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| 1454 | Active Users | Medium |
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| 1459 | Rectangles Area | Medium |
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| 1468 | Calculate Salaries | Medium |
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| 1501 | Countries You Can Safely Invest In | Medium |
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| 1532 | The Most Recent Three Orders | Medium |
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| 1549 | The Most Recent Orders For Each Product | Medium |
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| 1555 | Bank Account Summary | Medium |
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| 1596 | The Most Frequently Ordered Products For Each Customer | Medium |
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| 1613 | Find The Missing IDs | Medium |
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| 1699 | Number Of Calls Between Two Persons | Medium |
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| 1709 | Biggest Window Between Visits | Medium |
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| 1715 | Count Apples And Oranges | Medium |
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| 1747 | Leetflex Banned Accounts | Medium |
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| 1783 | Grand Slam Titles | Medium |
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| 1811 | Find Interview Candidates | Medium |
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| 1831 | Maximum Transaction Each Day | Medium |
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| 1841 | League Statistics | Medium |
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| 1843 | Suspicious Bank Accounts | Medium |
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| 1867 | Orders With Maximum Quantity Above Average | Medium |
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| 1875 | Group Employees of the Same Salary | Medium |
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| 1907 | Count Salary Categories | Medium |
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| 1934 | Confirmation Rate | Medium |
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| 1949 | Strong Friendship | Medium |
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| 1951 | All the Pairs With the Maximum Number of Common Followers | Medium |
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| 1988 | Find Cutoff Score for Each School | Medium |
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| 1990 | Count the Number of Experiments | Medium |
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Hard Problems
| No. | Problem | Difficulty | Solution | |||
|---|---|---|---|---|---|---|
| 185 | Department Top Three Salaries | Hard |
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| 262 | Trips And Users | Hard |
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| 569 | Median Employee Salary | Hard |
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| 571 | Find Median Given Frequency Of Numbers | Hard |
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| 579 | Find Cumulative Salary Of An Employee | Hard |
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| 601 | Human Traffic Of Stadium | Hard |
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| 615 | Average Salary: Departments VS Company | Hard |
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| 618 | Students Report By Geography | Hard |
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| 1097 | Game Play Analysis V | Hard |
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| 1127 | User Purchase Platform | Hard |
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| 1159 | Market Analysis II | Hard |
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| 1194 | Tournament Winners | Hard |
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| 1225 | Report Contiguous Dates | Hard |
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| 1336 | Number Of Transactions Per Visit | Hard |
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| 1369 | Get The Second Most Recent Activity | Hard |
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| 1384 | Total Sales Amount By Year | Hard |
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| 1412 | Find The Quiet Students In All Exams | Hard |
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| 1479 | Sales By Day Of The Week | Hard |
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| 1635 | Hopper Company Queries I | Hard |
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| 1645 | Hopper Company Queries II | Hard |
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| 1651 | Hopper Company Queries III | Hard |
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| 1767 | Find The Subtasks That Did Not Execute | Hard |
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| 1892 | Page Recommendations II | Hard |
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| 1917 | Leetcodify Friends Recommendations | Hard |
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| 1919 | Leetcodify Similar Friends | Hard |
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| 1972 | First and Last Call On the Same Day | Hard |
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