how do they encrypt and dencrypt

Answer 1

https://code.sololearn.com/cWQnECk5390t/?ref=app

Answer 2

https://code.sololearn.com/c2oD3kMGmfGQ/?ref=app

https://code.sololearn.com/c2AbgZnk20bs/?ref=app
https://code.sololearn.com/cIwpuGi5omyN/?ref=app
https://code.sololearn.com/cyA2EZAs8jiU/?ref=app