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LeetCode 코딩 테스트 - Analyze Subscription Conversion(LV.Medium)

Table: UserActivity+------------------+---------+| Column Name | Type | +------------------+---------+| user_id | int || activity_date | date || activity_type | varchar || activity_duration| int |+------------------+---------+(user_id, activity_date, activity_type) is the unique key for this table.activity_type is one of ('free_trial', 'paid', 'cancelled').activ..

LeetCode 코딩 테스트 - DNA Pattern Recognition(LV.Medium)

Table: Samples+----------------+---------+| Column Name | Type | +----------------+---------+| sample_id | int || dna_sequence | varchar || species | varchar |+----------------+---------+sample_id is the unique key for this table.Each row contains a DNA sequence represented as a string of characters (A, T, G, C) and the species it was collected from.Biologists are studyin..

Table: Signups+----------------+----------+| Column Name | Type |+----------------+----------+| user_id | int || time_stamp | datetime |+----------------+----------+user_id is the column of unique values for this table.Each row contains information about the signup time for the user with ID user_id. Table: Confirmations+----------------+----------+| Column Name | Type ..

Table: Accounts+-------------+------+| Column Name | Type |+-------------+------+| account_id | int || income | int |+-------------+------+account_id is the primary key (column with unique values) for this table.Each row contains information about the monthly income for one bank account. Write a solution to calculate the number of bank accounts for each salary category. The salary catego..

Table: Employee+-------------+------+| Column Name | Type |+-------------+------+| id | int || salary | int |+-------------+------+id is the primary key (column with unique values) for this table.Each row of this table contains information about the salary of an employee. Write a solution to find the nth highest salary from the Employee table. If there is no nth highest salary, r..

Table: Activity+--------------+---------+| Column Name | Type |+--------------+---------+| player_id | int || device_id | int || event_date | date || games_played | int |+--------------+---------+(player_id, event_date) is the primary key (combination of columns with unique values) of this table.This table shows the activity of players of some games.Each row is a recor..

Table: Movies+---------------+---------+| Column Name | Type |+---------------+---------+| movie_id | int || title | varchar |+---------------+---------+movie_id is the primary key (column with unique values) for this table.title is the name of the movie. Table: Users+---------------+---------+| Column Name | Type |+---------------+---------+| user_id | int |..

Table: Employee+-------------+------+| Column Name | Type |+-------------+------+| id | int || salary | int |+-------------+------+id is the primary key (column with unique values) for this table.Each row of this table contains information about the salary of an employee. Write a solution to find the second highest distinct salary from the Employee table. If there is no second hi..

Table: Sales+-------------+-------+| Column Name | Type |+-------------+-------+| sale_id | int || product_id | int || year | int || quantity | int || price | int |+-------------+-------+(sale_id, year) is the primary key (combination of columns with unique values) of this table.product_id is a foreign key (reference column) to Product table.Each row of this table..

Table: Logs+-------------+---------+| Column Name | Type |+-------------+---------+| id | int || num | varchar |+-------------+---------+In SQL, id is the primary key for this table.id is an autoincrement column starting from 1. Find all numbers that appear at least three times consecutively.Return the result table in any order.The result format is in the following exampl..