JavaScript
medium
Arrays
Search for a peak in an array
Given an array of integers, find the index of an element that is a peak, i.e., strictly greater than its neighbors. If t…
✅ 0 solved
📅 2026-05-11
PHP
medium
Arrays
Removing duplicates while preserving order
Write a program that takes an array of integers and removes all duplicates from it, preserving the original order of ele…
✅ 0 solved
📅 2026-05-11
Python
easy
Classes
```html
Class Book and search by year
```
Create a class `Book` with attributes `title`, `author`, and `year`. Implement the `__str__` method that returns a strin…
✅ 0 solved
📅 2026-05-11
TypeScript
easy
Async
Asynchronous parity check of a number
Write an asynchronous function `checkEven` that takes an integer and returns a Promise that resolves with the string 'ev…
✅ 0 solved
📅 2026-05-11
Rust
hard
Traits
Multi-phase polymorphic pipeline with traits
Implement a system of traits `Stage`, `Pipeline`, and `Transform` that allows building data processing pipelines. The `S…
✅ 0 solved
📅 2026-05-11
C++
easy
STL
Sum of the first N numbers using std::accumulate
Write a program that reads a natural number N, then N integers, and outputs their sum. Use the std::accumulate algorithm…
✅ 0 solved
📅 2026-05-11
Go
easy
Interfaces
Interface for geometric shapes
Create a Shape interface that contains the Area() float64 method. Implement the Circle (with a Radius float64 field) and…
✅ 0 solved
📅 2026-05-11
C#
hard
Delegates
Multi-level event processing system with delegates
Develop a program that simulates a multi-level event processing system. The input is a sequence of commands. Each comman…
✅ 0 solved
📅 2026-05-11
JavaScript
easy
Promises
Waiting for the first successful promise
Write a function `firstResolved(promises)` that takes an array of promises and returns a new promise that resolves with …
✅ 0 solved
📅 2026-05-11
Java
easy
Streams
Average word length in a string
Write a program that reads a string of text containing words separated by spaces. Using the Stream API, find the average…
✅ 0 solved
📅 2026-05-11
Kotlin
hard
Extensions
Report generator with extensions for nested collections
Write a Kotlin program that uses extension functions for `List` to generate a report: sequentially apply filtering by a …
✅ 0 solved
📅 2026-05-11
TypeScript
hard
Types
Type system: implement a conditional type for extracting object keys by value type
Write a function `extractKeysByValueType` that takes an object and a value type (as a string, for example `'string'` or …
✅ 0 solved
📅 2026-05-11
C++
hard
Recursion
Recursive construction of a balanced tree from prefix sums
Given an array of integers A of size N. It is required to recursively build a binary tree, where each node contains the …
✅ 0 solved
📅 2026-05-11
PHP
easy
Json
Checking JSON for correctness
Write a program that reads a string containing JSON and checks whether it is valid JSON. If the string is valid JSON, ou…
✅ 0 solved
📅 2026-05-11
Swift
hard
Structs
Route optimization using structures and a priority queue
Develop a `Route` structure representing a route with fields: `startCity` (String), `endCity` (String), `distance` (Int)…
✅ 0 solved
📅 2026-05-11
Go
hard
Structs
Intersection of objects with priorities
Two sets of structures describing objects with an identifier, type, and priority are given. It is necessary to find all …
✅ 0 solved
📅 2026-05-11
Python
hard
Arrays
Intersection of unique elements considering multiplicity
Given two lists of integers. Find the intersection of their unique elements, considering that each element can appear at…
✅ 0 solved
📅 2026-05-11
Java
hard
Generics
Generalized statistics collector with a functional interface
Implement a parameterized class `StatisticsCollector` that accepts arbitrary objects and computes statistics: count, sum…
✅ 0 solved
📅 2026-05-11
JavaScript
hard
Arrays
Multiple Word Formation: Finding All Possible Character Permutations
Given a string consisting of lowercase Latin letters. It is necessary to find and output all unique permutations of the …
✅ 0 solved
📅 2026-05-11
Rust
medium
Algorithms
Sorting by two keys with stability
Write a program that reads a list of strings, each containing an integer and a string separated by a space. Sort the lis…
✅ 0 solved
📅 2026-05-11
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