Does anyone know a resource for online verification of algorithms and data structures?

Question

Algorithms

Hello. About a year ago I came across a site where you could choose different algorithms to study the theory and then implement your solution and send it (solution) for analysis. (Something like codeforces.com) Now I can’t google it.
Maybe someone knows this?

Answer 1

leetcode.com

Answer 2

1) open the book "Algorithms and data structures in %language_name%"
2) implement
3) check
Plus, there are many collections on the net, like Python , C , JS , Java

Answer 3

coursera what?