As I'm refreshing/polishing my "competitive programming" skills, I'll gradually add my own solutions to problems.
The solutions are optimized, yet are my own form of thinking even if similar to others.
All solution have been compared to other solutions as well in order to make sure that the difficulty is categorized well, as well for the optimiziation.
Note: There might be coding problems duplicates between algorithms_pattern folder & other folders (e.g: by_data_structures)