Add solution for Project Euler problem 107 (#4066)

* Added solution for Project Euler problem 107

* Doctests and better variable names

* Type hints

* Small edits

* Forward reference for typing hint

* updating DIRECTORY.md

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>

fpringle committed 5y ago

80f5213df5726c9268b6e3771ae6aaf1b6e3bc82

Parent: 00e279e

Committed by GitHub <noreply@github.com> on 12/28/2020, 7:51:02 AM