feat(pandas): add problem 176

Author: IndexSeek

README.md

@@ -1,74 +1,74 @@
 # LeetCode SQL 50
 
-Fiddling around with DataFusion and PyArrow.
+Fiddling around with DataFusion, pandas, and PyArrow.
 
 ### Select
 
-- [X] [] 1757. [Recyclable and Low Fat Products](https://leetcode.com/problems/recyclable-and-low-fat-products) - Easy
-- [X] [] 584. [Find Customer Referee](https://leetcode.com/problems/find-customer-referee) - Easy
-- [X] [] 595. [Big Countries](https://leetcode.com/problems/big-countries) - Easy
-- [X] [] 1148. [Article Views I](https://leetcode.com/problems/article-views-i) - Easy
-- [X] [] 1683. [Invalid Tweets](https://leetcode.com/problems/invalid-tweets) - Easy
+- [X] [] [] 1757. [Recyclable and Low Fat Products](https://leetcode.com/problems/recyclable-and-low-fat-products) - Easy
+- [X] [] [] 584. [Find Customer Referee](https://leetcode.com/problems/find-customer-referee) - Easy
+- [X] [] [] 595. [Big Countries](https://leetcode.com/problems/big-countries) - Easy
+- [X] [] [] 1148. [Article Views I](https://leetcode.com/problems/article-views-i) - Easy
+- [X] [] [] 1683. [Invalid Tweets](https://leetcode.com/problems/invalid-tweets) - Easy
 
 ### Basic Joins
 
-- [X] [] 1378. [Replace Employee ID With The Unique Identifier](https://leetcode.com/problems/replace-employee-id-with-the-unique-identifier) - Easy
-- [X] [] 1068. [Product Sales Analysis I](https://leetcode.com/problems/product-sales-analysis-i) - Easy
-- [X] [] 1581. [Customer Who Visited but Did Not Make Any Transactions](https://leetcode.com/problems/customer-who-visited-but-did-not-make-any-transactions) - Easy
-- [X] [] 197. [Rising Temperature](https://leetcode.com/problems/rising-temperature) - Easy
-- [X] [] 1661. [Average Time of Process per Machine](https://leetcode.com/problems/average-time-of-process-per-machine) - Easy
-- [X] [] 577. [Employee Bonus](https://leetcode.com/problems/employee-bonus) - Easy
-- [X] [] 1280. [Students and Examinations](https://leetcode.com/problems/students-and-examinations) - Easy
-- [X] [] 570. [Managers with at Least 5 Direct Reports](https://leetcode.com/problems/managers-with-at-least-5-direct-reports) - Medium
-- [X] [] 1934. [Confirmation Rate](https://leetcode.com/problems/confirmation-rate) - Medium
+- [X] [] [] 1378. [Replace Employee ID With The Unique Identifier](https://leetcode.com/problems/replace-employee-id-with-the-unique-identifier) - Easy
+- [X] [] [] 1068. [Product Sales Analysis I](https://leetcode.com/problems/product-sales-analysis-i) - Easy
+- [X] [] [] 1581. [Customer Who Visited but Did Not Make Any Transactions](https://leetcode.com/problems/customer-who-visited-but-did-not-make-any-transactions) - Easy
+- [X] [] [] 197. [Rising Temperature](https://leetcode.com/problems/rising-temperature) - Easy
+- [X] [] [] 1661. [Average Time of Process per Machine](https://leetcode.com/problems/average-time-of-process-per-machine) - Easy
+- [X] [] [] 577. [Employee Bonus](https://leetcode.com/problems/employee-bonus) - Easy
+- [X] [] [] 1280. [Students and Examinations](https://leetcode.com/problems/students-and-examinations) - Easy
+- [X] [] [] 570. [Managers with at Least 5 Direct Reports](https://leetcode.com/problems/managers-with-at-least-5-direct-reports) - Medium
+- [X] [] [] 1934. [Confirmation Rate](https://leetcode.com/problems/confirmation-rate) - Medium
 
 ### Basic Aggregate Functions
 
-- [X] [X] 620. [Not Boring Movies](https://leetcode.com/problems/not-boring-movies) - Easy
-- [X] [] 1251. [Average Selling Price](https://leetcode.com/problems/average-selling-price) - Easy
-- [X] [] 1075. [Project Employees I](https://leetcode.com/problems/project-employees-i) - Easy
-- [X] [] 1633. [Percentage of Users Attended a Contest](https://leetcode.com/problems/percentage-of-users-attended-a-contest) - Easy
-- [X] [] 1211. [Queries Quality and Percentage](https://leetcode.com/problems/queries-quality-and-percentage) - Easy
-- [X] [] 1193. [Monthly Transactions I](https://leetcode.com/problems/monthly-transactions-i) - Medium
-- [X] [] 1174. [Immediate Food Delivery II](https://leetcode.com/problems/immediate-food-delivery-ii) - Medium
-- [X] [] 550. [Game Play Analysis IV](https://leetcode.com/problems/game-play-analysis-iv) - Medium
+- [X] [X] [] 620. [Not Boring Movies](https://leetcode.com/problems/not-boring-movies) - Easy
+- [X] [] [] 1251. [Average Selling Price](https://leetcode.com/problems/average-selling-price) - Easy
+- [X] [] [] 1075. [Project Employees I](https://leetcode.com/problems/project-employees-i) - Easy
+- [X] [] [] 1633. [Percentage of Users Attended a Contest](https://leetcode.com/problems/percentage-of-users-attended-a-contest) - Easy
+- [X] [] [] 1211. [Queries Quality and Percentage](https://leetcode.com/problems/queries-quality-and-percentage) - Easy
+- [X] [] [] 1193. [Monthly Transactions I](https://leetcode.com/problems/monthly-transactions-i) - Medium
+- [X] [] [] 1174. [Immediate Food Delivery II](https://leetcode.com/problems/immediate-food-delivery-ii) - Medium
+- [X] [] [] 550. [Game Play Analysis IV](https://leetcode.com/problems/game-play-analysis-iv) - Medium
 
 ### Sorting and Grouping
 
-- [X] [] 2356. [Number of Unique Subjects Taught by Each Teacher](https://leetcode.com/problems/number-of-unique-subjects-taught-by-each-teacher) - Easy
-- [X] [] 1141. [User Activity for the Past 30 Days I](https://leetcode.com/problems/user-activity-for-the-past-30-days-i) - Easy
-- [X] [] 1070. [Product Sales Analysis III](https://leetcode.com/problems/product-sales-analysis-iii) - Medium
-- [X] [] 596. [Classes More Than 5 Students](https://leetcode.com/problems/classes-more-than-5-students) - Easy
-- [X] [] 1729. [Find Followers Count](https://leetcode.com/problems/find-followers-count) - Easy
-- [X] [] 619. [Biggest Single Number](https://leetcode.com/problems/biggest-single-number) - Easy
-- [X] [] 1045. [Customers Who Bought All Products](https://leetcode.com/problems/customers-who-bought-all-products) - Medium
+- [X] [] [] 2356. [Number of Unique Subjects Taught by Each Teacher](https://leetcode.com/problems/number-of-unique-subjects-taught-by-each-teacher) - Easy
+- [X] [] [] 1141. [User Activity for the Past 30 Days I](https://leetcode.com/problems/user-activity-for-the-past-30-days-i) - Easy
+- [X] [] [] 1070. [Product Sales Analysis III](https://leetcode.com/problems/product-sales-analysis-iii) - Medium
+- [X] [] [] 596. [Classes More Than 5 Students](https://leetcode.com/problems/classes-more-than-5-students) - Easy
+- [X] [] [] 1729. [Find Followers Count](https://leetcode.com/problems/find-followers-count) - Easy
+- [X] [] [] 619. [Biggest Single Number](https://leetcode.com/problems/biggest-single-number) - Easy
+- [X] [] [] 1045. [Customers Who Bought All Products](https://leetcode.com/problems/customers-who-bought-all-products) - Medium
 
 ### Advanced Select and Joins
 
-- [X] [] 1731. [The Number of Employees Which Report to Each Employee](https://leetcode.com/problems/the-number-of-employees-which-report-to-each-employee) - Easy
-- [X] [] 1789. [Primary Department for Each Employee](https://leetcode.com/problems/primary-department-for-each-employee) - Easy
-- [X] [] 610. [Triangle Judgement](https://leetcode.com/problems/triangle-judgement) - Easy
-- [X] [] 180. [Consecutive Numbers](https://leetcode.com/problems/consecutive-numbers) - Medium
-- [X] [] 1164. [Product Price at a Given Date](https://leetcode.com/problems/product-price-at-a-given-date) - Medium
-- [X] [] 1204. [Last Person to Fit in the Bus](https://leetcode.com/problems/last-person-to-fit-in-the-bus) - Medium
-- [X] [] 1907. [Count Salary Categories](https://leetcode.com/problems/count-salary-categories) - Medium
+- [X] [] [] 1731. [The Number of Employees Which Report to Each Employee](https://leetcode.com/problems/the-number-of-employees-which-report-to-each-employee) - Easy
+- [X] [] [] 1789. [Primary Department for Each Employee](https://leetcode.com/problems/primary-department-for-each-employee) - Easy
+- [X] [] [] 610. [Triangle Judgement](https://leetcode.com/problems/triangle-judgement) - Easy
+- [X] [] [] 180. [Consecutive Numbers](https://leetcode.com/problems/consecutive-numbers) - Medium
+- [X] [] [] 1164. [Product Price at a Given Date](https://leetcode.com/problems/product-price-at-a-given-date) - Medium
+- [X] [] [] 1204. [Last Person to Fit in the Bus](https://leetcode.com/problems/last-person-to-fit-in-the-bus) - Medium
+- [X] [] [] 1907. [Count Salary Categories](https://leetcode.com/problems/count-salary-categories) - Medium
 
 ### Subqueries
 
-- [X] [] 1978. [Employees Whose Manager Left the Company](https://leetcode.com/problems/employees-whose-manager-left-the-company) - Easy
-- [X] [] 626. [Exchange Seats](https://leetcode.com/problems/exchange-seats) - Medium
-- [X] [] 1341. [Movie Rating](https://leetcode.com/problems/movie-rating) - Medium
-- [] [X] 1321. [Restaurant Growth](https://leetcode.com/problems/restaurant-growth) - Medium
-- [X] [] 602. [Friend Requests II: Who Has the Most Friends](https://leetcode.com/problems/friend-requests-ii-who-has-the-most-friends) - Medium
-- [X] [] 585. [Investments in 2016](https://leetcode.com/problems/investments-in-2016) - Medium
-- [X] [] 185. [Department Top Three Salaries](https://leetcode.com/problems/department-top-three-salaries) - Hard
+- [X] [] [] 1978. [Employees Whose Manager Left the Company](https://leetcode.com/problems/employees-whose-manager-left-the-company) - Easy
+- [X] [] [] 626. [Exchange Seats](https://leetcode.com/problems/exchange-seats) - Medium
+- [X] [] [] 1341. [Movie Rating](https://leetcode.com/problems/movie-rating) - Medium
+- [] [X] [] 1321. [Restaurant Growth](https://leetcode.com/problems/restaurant-growth) - Medium
+- [X] [] [] 602. [Friend Requests II: Who Has the Most Friends](https://leetcode.com/problems/friend-requests-ii-who-has-the-most-friends) - Medium
+- [X] [] [] 585. [Investments in 2016](https://leetcode.com/problems/investments-in-2016) - Medium
+- [X] [] [] 185. [Department Top Three Salaries](https://leetcode.com/problems/department-top-three-salaries) - Hard
 
 ### Advanced String Functions / Regex / Clause
 
-- [X] [] 1667. [Fix Names in a Table](https://leetcode.com/problems/fix-names-in-a-table) - Easy
-- [X] [] 1527. [Patients With a Condition](https://leetcode.com/problems/patients-with-a-condition) - Easy
-- [X] [] 196. [Delete Duplicate Emails](https://leetcode.com/problems/delete-duplicate-emails) - Easy
-- [X] [X] 176. [Second Highest Salary](https://leetcode.com/problems/second-highest-salary) - Medium
-- [] [X] 1484. [Group Sold Products By The Date](https://leetcode.com/problems/group-sold-products-by-the-date) - Easy
-- [X] [] 1327. [List the Products Ordered in a Period](https://leetcode.com/problems/list-the-products-ordered-in-a-period) - Easy
-- [X] [] 1517. [Find Users With Valid E-Mails](https://leetcode.com/problems/find-users-with-valid-e-mails) - Easy
+- [X] [] [] 1667. [Fix Names in a Table](https://leetcode.com/problems/fix-names-in-a-table) - Easy
+- [X] [] [] 1527. [Patients With a Condition](https://leetcode.com/problems/patients-with-a-condition) - Easy
+- [X] [] [] 196. [Delete Duplicate Emails](https://leetcode.com/problems/delete-duplicate-emails) - Easy
+- [X] [X] [X] 176. [Second Highest Salary](https://leetcode.com/problems/second-highest-salary) - Medium
+- [] [X] [] 1484. [Group Sold Products By The Date](https://leetcode.com/problems/group-sold-products-by-the-date) - Easy
+- [X] [] [] 1327. [List the Products Ordered in a Period](https://leetcode.com/problems/list-the-products-ordered-in-a-period) - Easy
+- [X] [] [] 1517. [Find Users With Valid E-Mails](https://leetcode.com/problems/find-users-with-valid-e-mails) - Easy

problems/pandas.py

@@ -0,0 +1,31 @@
+"""Solutions to LeetCode problems in pandas."""
+
+import pandas as pd
+
+
+def problem_176(employee: pd.DataFrame) -> pd.DataFrame:
+    """Find the second highest distinct salary from the Employee table.
+
+    If there is no second highest salary, return null.
+
+    Parameters
+    ----------
+    employee : pd.DataFrame
+        The table containing employee salary data.
+
+    Returns
+    -------
+    pd.DataFrame
+
+    """
+    filtered = (
+        employee[["salary"]]
+        .drop_duplicates()
+        .sort_values("salary", ascending=False)
+        .reset_index(drop=True)
+    )
+    second_highest_salary = filtered.iloc[1]["salary"] if len(filtered) > 1 else None
+    result = pd.DataFrame([second_highest_salary], columns=["SecondHighestSalary"])
+    if result.empty:
+        return pd.DataFrame([None], columns=["SecondHighestSalary"])
+    return result

tests/test_pandas.py

@@ -0,0 +1,35 @@
+import pandas as pd
+import pytest
+
+from problems.pandas import problem_176
+
+
+@pytest.mark.parametrize(
+    "input_data, expected_data",
+    [
+        pytest.param(
+            {"salary": [100, 200, 300]},
+            {"SecondHighestSalary": [200]},
+            id="distinct_salaries",
+        ),
+        pytest.param(
+            {"salary": [100, 200, 200, 300]},
+            {"SecondHighestSalary": [200]},
+            id="multiple_second_highest",
+        ),
+        pytest.param(
+            {"salary": [100]}, {"SecondHighestSalary": [None]}, id="single_salary"
+        ),
+        pytest.param(
+            {"salary": [100, 100, 100]},
+            {"SecondHighestSalary": [None]},
+            id="all_salaries_same",
+        ),
+        pytest.param({"salary": []}, {"SecondHighestSalary": [None]}, id="empty_table"),
+    ],
+)
+def test_problem_176(input_data, expected_data):
+    table = pd.DataFrame(input_data)
+    expected_table = pd.DataFrame(expected_data)
+    result = problem_176(table)
+    assert result.equals(expected_table)