Advent of Code is an Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like. People use them as interview prep, company training, university coursework, practice problems, a speed contest, or to challenge each other.
https://adventofcode.com/2023/day/1
https://adventofcode.com/2023/day/2
https://adventofcode.com/2023/day/3
https://adventofcode.com/2023/day/4