Contribution #1681

Problem: en/4.2.12

Added Luis's English solutions of 4.2.11 and 4.2.12

Editor: Luis Daniel Fernández Quintana ( @Luisito )

Time: June 26, 2024 at 01:24 AM

GitHub commit: 12c27b249076055cda6276a2d81fef3cabc70b98

+109 -9 lines changed