https://adventofcode.com solutions.
The non-D solutions under 2019/*/d/ are not mine: they are all taken from anonymous postings, with very minor modifications. These are usually for "rewrite it in D" fun: for example, 2019/3/d/crystal.cr is a nice-looking and decently-performing Crystal solution, and accompanying it is 2019/3/d/d_crystal.d , a D solution in the exact style of the Crystal solution.
Most of these solutions are missing for now, and will be added later.