A free app for Android, by Ievgen Ovsii.
Algorithms and Data Structures is an interactive learning course, which aims to teach the basics of data structures and algorithms to students of any level.
Data structures are a set of values that are used to store information. In most cases, this information is used for the purpose of managing and processing data. The structure may be real (e.g., an array), symbolic (e., a sequence), or any combination of the two.
Algorithms are a set of steps that are performed to solve a problem. Each step consists of a sequence of instructions that define how the solution should be obtained.
The interactive course consists of a number of lessons. In each lesson, the user is provided with a new problem and a solution. The user is required to perform the steps of the solution in order to obtain the correct answer.
The interactive course is designed to be used by both students and teachers.