Kotlin
medium
Data classes
Class Schedule: Overriding equals and hashCode
Create a data class `Lesson` with fields: name (String), teacher (String), classroom (String), day of week (Int, 1-7), l…
✅ 0 solved
📅 2026-05-11
Java
hard
Algorithms
Counting sort with order restoration
Given an array of integers. It is necessary to sort it in ascending order using the counting sort algorithm. However, fo…
✅ 0 solved
📅 2026-05-11
JavaScript
easy
Algorithms
Sort by string length
Write a function that takes an array of strings and returns it sorted by ascending string length. If the lengths are equ…
✅ 0 solved
📅 2026-05-11
Go
hard
Math
Greatest common divisor for all subsegments
Given an array of integers a of length n. For each possible subsegment [l, r] (1 ≤ l ≤ r ≤ n), it is necessary to comput…
✅ 0 solved
📅 2026-05-11
Swift
medium
Optional values
Safe extraction of a value from a chain of optionals
You are given a string containing integers separated by spaces. Some numbers may be missing (replaced by '?'). Write a f…
✅ 0 solved
📅 2026-05-11
C#
easy
LINQ
Filter even numbers and sort in descending order
Write a program that reads a sequence of integers separated by spaces, uses LINQ to filter only even numbers, sorts them…
✅ 0 solved
📅 2026-05-11
Rust
medium
Enums
Determining the type of shape by coordinates
Write a program that reads the number of points (from 3 to 10) and their coordinates (x, y). Use an enumeration (enum) t…
✅ 0 solved
📅 2026-05-11
PHP
easy
Regex
Checking email format using a regular expression
Write a PHP program that reads a string from standard input and checks whether it matches a simple email pattern: local …
✅ 0 solved
📅 2026-05-11
TypeScript
easy
Classes
Class Student with the getFullName method
Create a class `Student` that has two public fields: `firstName` (string) and `lastName` (string). The class constructor…
✅ 0 solved
📅 2026-05-11
Python
medium
Recursion
Recursive check of bracket balance
Write a recursive function to check the correctness of bracket placement in a string. The string consists only of the ch…
✅ 0 solved
📅 2026-05-11
JavaScript
hard
Math
Calculating the sum of digits of the factorial of a number N
Write a program that calculates the sum of the digits of the factorial of a given number N. The factorial of a number N …
✅ 0 solved
📅 2026-05-11
Java
medium
Math
Sum of digits of a number raised to a power
Given a natural number N and a non-negative integer K. Raise N to the power K and find the sum of the digits of the resu…
✅ 0 solved
📅 2026-05-11
Go
medium
Goroutines
Parallel sum of squares
Write a Go program that reads two integers n and m, then reads n lines, each containing m integers. It is necessary to c…
✅ 0 solved
📅 2026-05-11
Kotlin
easy
Classes
Class Book: creation and output of information
Create a class Book with fields title, author, and year. Implement a main function that reads three strings: title, auth…
✅ 0 solved
📅 2026-05-11
C++
medium
Math
Sum of digits of a number raised to the power k
Given a natural number n and a natural number k. Raise n to the power of k, then find the sum of the digits of the resul…
✅ 0 solved
📅 2026-05-11
C#
hard
Classes
Class inheritance graph with virtual methods
Develop a class system to represent a hierarchy of geometric shapes with a virtual method for calculating area. The base…
✅ 0 solved
📅 2026-05-11
PHP
hard
Algorithms
Merge sort with inversion counting
Given an array of integers, it is necessary to implement a merge sort algorithm that also counts the number of inversion…
✅ 0 solved
📅 2026-05-11
Swift
easy
Classes
```html
Class Book with an information output method
```
Create a class `Book` with three properties: `title`, `author`, and `year`. Implement a method `displayInfo()` that outp…
✅ 0 solved
📅 2026-05-11
Rust
easy
Structs
Structure Point: distance to the origin
Define a structure Point with fields x and y (integers). Write a program that reads integers x and y, creates an instanc…
✅ 0 solved
📅 2026-05-11
Python
easy
Functions
Function for calculating the arithmetic mean
Write a function `average` that takes a list of numbers and returns their arithmetic mean. If the list is empty, the fun…
✅ 0 solved
📅 2026-05-11
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