2019advent

1. https://docs.google.com/spreadsheets/d/1nl07MquXM0mlGzEfnIC5Q8WexDqYRsHCvKS4uKuK37k/edit?usp=sharing
2. https://play.golang.org/p/iE5EvquZopY
3. https://play.golang.org/p/a4czDlVZK8c
4. https://play.golang.org/p/WHr-5klNggZ
5. https://play.golang.org/p/HZPE4lQ0g5g