Introduction

In this blog post, we'll share the most commonly asked coding interview questions at Ozon. If you don't have months to study for your interviews, you can use AI tools like Chatmagic to generate solutions quickly and efficiently - helping you pass the interviews and get the job offer!

Problem #1: Department Top Three Salaries

Table: Employee +--------------+---------+ | Column Name | Type | +--------------+---------+ | id | int | | name | varchar | | salary | int | | departmentId | int | +--------------+---------+ id is the primary key (column with unique values) for this table. departmentId is a foreign key (reference column) of the ID from the Department table. Each row of this table indicates the ID, name, and salary of an employee. It also contains the ID of their department. Table: Department +-------------+---------+ | Column Name | Type | +-------------+---------+ | id | int | | name | varchar | +-------------+---------+ id is the primary key (column with unique values) for this table. Each row of this table indicates the ID of a department and its name. A company's executives are interested in seeing who earns the most money in each of the company's departments. A high earner in a department is an employee who has a salary in the top three unique salaries for that department. Write a solution to find the employees who are high earners in each of the departments. Return the result table in any order. The result format is in the following example. Example 1: Input: Employee table: +----+-------+--------+--------------+ | id | name | salary | departmentId | +----+-------+--------+--------------+ | 1 | Joe | 85000 | 1 | | 2 | Henry | 80000 | 2 | | 3 | Sam | 60000 | 2 | | 4 | Max | 90000 | 1 | | 5 | Janet | 69000 | 1 | | 6 | Randy | 85000 | 1 | | 7 | Will | 70000 | 1 | +----+-------+--------+--------------+ Department table: +----+-------+ | id | name | +----+-------+ | 1 | IT | | 2 | Sales | +----+-------+ Output: +------------+----------+--------+ | Department | Employee | Salary | +------------+----------+--------+ | IT | Max | 90000 | | IT | Joe | 85000 | | IT | Randy | 85000 | | IT | Will | 70000 | | Sales | Henry | 80000 | | Sales | Sam | 60000 | +------------+----------+--------+ Explanation: In the IT department: - Max earns the highest unique salary - Both Randy and Joe earn the second-highest unique salary - Will earns the third-highest unique salary In the Sales department: - Henry earns the highest salary - Sam earns the second-highest salary - There is no third-highest salary as there are only two employees Constraints: There are no employees with the exact same name, salary and department.

Topics: Database

Problem #2: Monotonic Array

An array is monotonic if it is either monotone increasing or monotone decreasing. An array nums is monotone increasing if for all i <= j, nums[i] <= nums[j]. An array nums is monotone decreasing if for all i <= j, nums[i] >= nums[j]. Given an integer array nums, return true if the given array is monotonic, or false otherwise. Example 1: Input: nums = [1,2,2,3] Output: true Example 2: Input: nums = [6,5,4,4] Output: true Example 3: Input: nums = [1,3,2] Output: false Constraints: 1 <= nums.length <= 105 -105 <= nums[i] <= 105

Topics: Array